Light connectivity and autonomous mobility

ABSTRACT

Light and/or Inactive state connectivity and/or autonomous mobility techniques are contemplated. A WTRU may, for example, have an inactive/idle mode, a light connected/loosely connected/Inactive mode and/or a connected/fully connected/Active mode. A WTRU in light connected mode may have a WTRU context stored in a RAN. A WTRU may perform an area monitoring procedure while in light connected state. A WTRU may engage in autonomous mobility during light connectivity. A WTRU may move within a logical area (e.g., a RAN paging area), perhaps without notifying the network. The WTRU may provide notice when it has moved outside a logical area (e.g., update RAN paging area). Mobility in light connected state may be network controlled (e.g., to enable handover when data transfer may be allowed and/or ongoing). A WTRU may be reachable during a light connectivity state. A WTRU may engage in autonomous mobility during light connectivity and/or an Inactive state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Pat. ApplicationNo. 62/372,973 filed on Aug. 10, 2016; U.S. Provisional Pat. ApplicationNo. 62/400,837, filed on Sep. 28, 2016; U.S. Provisional Pat.Application No. 62/442,109 filed on Jan. 4, 2017; U.S. Provisional Pat.Application No. 62/453,128 filed on Feb. 1, 2017; and U.S. ProvisionalPat. Application No. 62/475,117 filed on Mar. 22, 2017, the contents ofall of which being hereby incorporated by reference as if fullyset-forth herein in their respective entirety, for all purposes.

BACKGROUND

Mobile communications are in continuous evolution and are already at thedoorstep of their fifth incarnation - 5G. As with previous generations,new use cases largely contributed in setting the requirements for thenew system. It is expected that the 5G air interface may enable improvedbroadband performance (IBB), industrial control and communications(ICC), vehicular applications (V2X), and/or massive machine-typecommunications (mMTC).

Deployments of a 5G network may include stand-alone systems, and/or mayinclude a phased approach, e.g., in combination with existingdeployments and/or with existing technologies (such as LTE and/or anevolution thereof). Combinations with existing technologies may involveradio access network components and/or core network components.

SUMMARY

Systems, methods, and/or instrumentalities are disclosed for lightconnectivity and/or autonomous mobility. A wireless transmit/receiveunit (WTRU) may, for example, have an inactive/idle mode, a lightconnected/loosely connected/Inactive mode and/or a connected/fullyconnected/Active mode. A WTRU in light connected mode may have a WTRUcontext stored in a Radio Access Network (RAN). A WTRU may perform anarea monitoring procedure while in light connected state. As describedherein, a light connected state (and/or lightly connected state) maycorrespond to an INACTIVE state. A WTRU may engage in autonomousmobility during light connectivity and/or in an INACTIVE state. A WTRUmay move within a logical area (e.g., a RAN paging area) withoutnotifying the network, but may provide notice when it has moved outsidea logical area (e.g., update RAN paging area). Mobility in lightconnected state may be network controlled (e.g., to enable handover whendata transfer may be allowed and/or ongoing). A WTRU may be reachableduring a light connectivity state. A WTRU may engage in autonomousmobility during light connectivity. A WTRU may perform data transferwithout leaving light connected state. A WTRU may autonomouslytransition to a light connectivity state. A network may signal a WTRU totransition a light connectivity state. A transition from inactive tolight connectivity may reduce signaling overhead and/or latency/delaysthat may otherwise occur before a WTRU may perform a first transmissionin active mode. A WTRU may transition to connected mode with low latencyand/or low overhead.

A WTRU may be in communication with a wireless communication network.The WTRU may comprise a memory. The WTRU may comprise a processor. Theprocessor may be configured to determine to transition to a RadioResource Control (RRC) INACTIVE state based on a first condition. Theprocessor may be configured to transition to the RRC INACTIVE state uponan occurrence of the first condition. The processor may be configured todetermine that uplink (UL) data is to be sent to a node of the wirelesscommunication network. The processor may be configured to determine totransmit the UL data in the RRC INACTIVE state and/or a RRC CONNECTEDstate based on a second condition being satisfied or unsatisfied. Theprocessor may be configured to determine to remain in the INACTIVE stateand send the UL data based on the second condition being satisfied. Theprocessor may be configured to transition to the RRC CONNECTED state andsend the UL data based on the second condition being unsatisfied. TheWTRU may comprise a transmitter. The transmitter may be configured totransmit the UL data in the RRC INACTIVE state and/or the RRC CONNECTEDstate to the node of the wireless communication network.

A WTRU in a light connected mode may perform a data transfer withoutentering an active mode, for example, using one or more initial accessmessages between the WTRU and the network before the WTRU enters theactive mode.

A WTRU may transition to a light connected state, for example, based onvolume of data transmission, inactivity, type of service, a configuredbehavior, received downlink (DL) paging and/or a default initializationstate.

WTRU actions in a light connected state may include, for example,activation of a light connectivity configuration, WTRU identityassociated with light connected state, handling radio resources and/orenabling functions based on location relative to a logical area.

WTRU reachability for a light connected stated may include, for example,realizing a RAN paging area (PA), triggers to perform a RAN PA updateand/or interaction between RAN paging area and tracking area.

Low-latency transition to a connected mode from light connected statemay include, for example, non-abstract syntax notation (ASN) signaling,dedicated resources for fast reconnection, piggybacking reconnectionwith data and/or on-demand system information.

Reconnection failures may be handled, for example, using a pre-existingcontext in the RAN and/or core network.

Light connectivity state may be exited based on WTRU-based rules, suchas elapsed time, inactivity, WTRU location, mobility state, arrival ofunsupported services (e.g., new data becoming available for a servicethat is not supported in the light connectivity state, or theestablishment thereof), RAN paging failure and/or unsupported cell. WTRUstate mismatch with the core network control function may be handledduring load balancing.

WTRU measurement procedures for light connectivity state, may include,for example, using reference signals different from those for connectedmode measurements, evaluating a quality of a RAN paging channel and/orpower consumption reduction, such as restriction of neighbormeasurements in light connected state.

WTRU autonomous mobility may include, for example, triggering events,prioritization rules, timing of paging reception, WTRU configurationhandling based on association between a received configuration and anedge control function, implicit information based on a presence of areference signal, broadcast information and/or WTRU location. Proceduresare provided for mobility and/or context reuse for inter-radio accesstechnology (inter-RAT) light connectivity.

WTRU context handling (e.g., layer 2 and/or layer 2 configuration) inlight connected state may be a function of, for example, location,deployment, active services/slice/flow, validity time, and/or dataactivity. There may be a per-transaction persistence of a layer 2 state.

Data transfer during light connectivity may include, for example,restrictions on data volume, validity of configured resources, type ofservice, direction of transfer, type of protocol data unit (PDU) and/orlocation.

RAN paging message handling may include, for example, determination ofRAN paging channel resources, a relation between RAN and core network(CN) paging and/or WTRU identity in paging messages.

WTRU data transmission in light connected state may use initial accessmessages, which may include, for example, data transmission in a randomaccess resource, data transmission in a contention based resource and/ordata transmission in message 3 (MSG3).

Inter-RAT state transition may be provided. WTRU behavior may beaffected during an inactive state, for example, by providing for WTRUbehavior during an extended scheduling period in an inactive state.

A WTRU may determine that one or more security parameters associatedwith a key derivation are invalid, insufficient, and/or outdated. TheWTRU may initiate, based on the determination that the one or moresecurity parameters are invalid, insufficient, and/or outdated, arecovery procedure to enable a security level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed devices, systems, and/ortechniques may be implemented.

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to one or more devices, systems,processes, and/or techniques described herein.

FIG. 1C is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to one or moredevices, systems, processes, and/or techniques described herein.

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to one or more devices, systems,processes, and/or techniques described herein.

FIG. 2 is an illustration of an example technique of uplink (UL) datatransmission in an INACTIVE state and/or CONNECTED state.

FIG. 3 is an illustration of an example technique of autonomous mobilityand/or uplink (UL) data transmission in an INACTIVE state and/orCONNECTED state.

FIG. 4 is an example illustration of overlapping and/or non-overlappingpaging occasions.

DETAILED DESCRIPTION

A detailed description of illustrative embodiments will now be describedwith reference to the various Figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be examples and in no way limitthe scope of the application.

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM(UW-OFDM), resource block-filtered OFDM, filter bank multicarrier(FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a RAN104/113, a CN 106/115, a public switched telephone network (PSTN) 108,the Internet 110, and other networks 112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 102 a,102 b, 102 c, 102 d may be any type of device configured to operateand/or communicate in a wireless environment. By way of example, theWTRUs 102 a, 102 b, 102 c, 102 d, any of which may be referred to as a“station” and/or a “STA”, may be configured to transmit and/or receivewireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106/115, the Internet110, and/or the other networks 112. By way of example, the base stations114 a, 114 b may be a base transceiver station (BTS), a Node-B, an eNodeB, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller,an access point (AP), a wireless router, and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104/113, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals on one or morecarrier frequencies, which may be referred to as a cell (not shown).These frequencies may be in licensed spectrum, unlicensed spectrum, or acombination of licensed and unlicensed spectrum. A cell may providecoverage for a wireless service to a specific geographical area that maybe relatively fixed or that may change over time. The cell may furtherbe divided into cell sectors. For example, the cell associated with thebase station 114 a may be divided into three sectors. Thus, in oneembodiment, the base station 114 a may include three transceivers, i.e.,one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and mayutilize multiple transceivers for each sector of the cell. For example,beamforming may be used to transmit and/or receive signals in desiredspatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104/113 and the WTRUs 102 a,102 b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 115/116/117 using wideband CDMA (WCDMA).WCDMA may include communication protocols such as High-Speed PacketAccess (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-SpeedDownlink (DL) Packet Access (HSDPA) and/or High-Speed UL Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using New Radio (NR).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., a eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106/115.

The RAN 104/113 may be in communication with the CN 106/115, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. The data may have varying qualityof service (QoS) requirements, such as differing throughputrequirements, latency requirements, error tolerance requirements,reliability requirements, data throughput requirements, mobilityrequirements, and the like. The CN 106/115 may provide call control,billing services, mobile location-based services, pre-paid calling,Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 1A, it will be appreciated that the RAN 104/113 and/or theCN 106/115 may be in direct or indirect communication with other RANsthat employ the same RAT as the RAN 104/113 or a different RAT. Forexample, in addition to being connected to the RAN 104/113, which may beutilizing a NR radio technology, the CN 106/115 may also be incommunication with another RAN (not shown) employing a GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106/115 may also serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104/113 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors, the sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor; an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, and/ora humidity sensor.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) anddownlink (e.g., for reception) may be concurrent and/or simultaneous.The full duplex radio may include an interference management unit 139 toreduce and or substantially eliminate self-interference via eitherhardware (e.g., a choke) or signal processing via a processor (e.g., aseparate processor (not shown) or via processor 118). In an embodiment,the WRTU 102 may include a half-duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for either the UL (e.g., for transmission) or thedownlink (e.g., for reception)).

FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 1C, the eNode-Bs 160a, 160 b, 160 c may communicate with one another over an X2 interface.

The CN 106 shown in FIG. 1C may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (or PGW) 166. While each of the foregoing elements are depictedas part of the CN 106, it will be appreciated that any of these elementsmay be owned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have an access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in to and/or out of the BSS. Traffic to STAs that originatesfrom outside the BSS may arrive through the AP and may be delivered tothe STAs. Traffic originating from STAs to destinations outside the BSSmay be sent to the AP to be delivered to respective destinations.Traffic between STAs within the BSS may be sent through the AP, forexample, where the source STA may send traffic to the AP and the AP maydeliver the traffic to the destination STA. The traffic between STAswithin a BSS may be considered and/or referred to as peer-to-peertraffic. The peer-to-peer traffic may be sent between (e.g., directlybetween) the source and destination STAs with a direct link setup (DLS).In certain representative embodiments, the DLS may use an 802.11e DLS oran 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS)mode may not have an AP, and the STAs (e.g., all of the STAs) within orusing the IBSS may communicate directly with each other. The IBSS modeof communication may sometimes be referred to herein as an “ad-hoc” modeof communication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.The primary channel may be the operating channel of the BSS and may beused by the STAs to establish a connection with the AP. In certainrepresentative embodiments, Carrier Sense Multiple Access with CollisionAvoidance (CSMA/CA) may be implemented, for example in in 802.11systems. For CSMA/CA, the STAs (e.g., every STA), including the AP, maysense the primary channel. If the primary channel is sensed/detectedand/or determined to be busy by a particular STA, the particular STA mayback off. One STA (e.g., only one station) may transmit at any giventime in a given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.1 1af and 802.11ah.The channel operating bandwidths, and carriers, are reduced in 802.11afand 802.11ah relative to those used in 802.11n, and 802.11ac. 802.1 1afsupports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications, such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode), transmitting to the AP, the entire available frequency bands maybe considered busy even though a majority of the frequency bands remainsidle and may be available.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 113 and the CN 115according to an embodiment. As noted above, the RAN 113 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 113 may also be in communication with theCN 115.

The RAN 113 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 113 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containingvarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, dual connectivity, interworkingbetween NR and E-UTRA, routing of user plane data towards User PlaneFunction (UPF) 184 a, 184 b, routing of control plane informationtowards Access and Mobility Management Function (AMF) 182 a, 182 b andthe like. As shown in FIG. 1D, the gNBs 180 a, 180 b, 180 c maycommunicate with one another over an Xn interface.

The CN 115 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a,184b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whileeach of the foregoing elements are depicted as part of the CN 115, itwill be appreciated that any of these elements may be owned and/oroperated by an entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different PDU sessions with differentrequirements), selecting a particular SMF 183 a, 183 b, management ofthe registration area, termination of NAS signaling, mobilitymanagement, and the like. Network slicing may be used by the AMF 182 a,182 b in order to customize CN support for WTRUs 102 a, 102 b, 102 cbased on the types of services being utilized WTRUs 102 a, 102 b, 102 c.For example, different network slices may be established for differentuse cases such as services relying on ultra-reliable low latency (URLLC)access, services relying on enhanced massive mobile broadband (eMBB)access, services for machine type communication (MTC) access, and/or thelike. The AMF 162 may provide a control plane function for switchingbetween the RAN 113 and other RANs (not shown) that employ other radiotechnologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP accesstechnologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN115 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 115 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating UE IP address,managing PDU sessions, controlling policy enforcement and QoS, providingdownlink data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 113 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering downlink packets, providing mobility anchoring, and thelike.

The CN 115 may facilitate communications with other networks. Forexample, the CN 115 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 115 and the PSTN 108. In addition, the CN 115may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a localData Network (DN) 185 a, 185 b through the UPF 184 a, 184 b via the N3interface to the UPF 184 a, 184 b and an N6 interface between the UPF184 a, 184 b and the DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-ab, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or may performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

An air interface, e.g., for a new radio (NR) access technology in a 5Gsystem, may support a variety of use cases, such as improved broadbandperformance (IBB), Industrial control and communications (ICC) and/orvehicular applications (V2X) and/or Massive Machine-Type Communications(mMTC). Use cases may have associated support in an air interface (e.g.,5G air interface).

An air interface may support, for example, ultra-low transmissionlatency (LLC), ultra-reliable transmission (URC) and/or MTC operation(including narrowband operation).

Support for ultra-low transmission latency (LLC) may comprise, forexample, air interface latency such as 1 ms RTT and/or TTIs between 100us to 250 us. Support may be provided for ultra-low access latency(e.g., time from initial system access until the completion of thetransmission of the first user plane data unit). End-to-end (e2e)latency less than 10 ms may be supported, for example, for IC and/orV2X.

Support for ultra-reliable transmission (URC) may comprise, for example,improved transmission reliability, such as 99.999% transmission successand/or service availability. Support may be provided for mobility speedin the range of 0-500 km/h. Packet Loss Ratio of less than 10e⁻⁶ may besupported, for example, for IC and/or V2X.

Support for MTC operation may comprise, for example, air interfacesupport for narrowband operation (e.g., using less than 200 KHz),extended battery life (e.g., up to 15 years of autonomy) and/or minimalcommunication overhead for small and/or infrequent data transmissions(e.g., low data rate in the range of 1-100 kbps with access latency ofseconds to hours).

A 5gFLEX/New Radio (NR) system may be implemented with OFDM and/or otherwaveforms for uplink and/or downlink. Description of examples herein maybe non-limiting. Examples may be applicable and/or adaptable to otherwaveforms and/or wireless technologies.

OFDM may be used as a signal format for data transmissions, e.g., in LTEand/or IEEE 802.11. OFDM may efficiently divide spectrum into multipleparallel orthogonal subbands. A (e.g., one or more, or each) subcarriermay be shaped using a rectangular window in the time domain, which maylead to sinc-shaped subcarriers in the frequency domain. OFDMA may relyon (e.g., perfect) frequency synchronization and/or tight management ofuplink timing alignment within the duration of the cyclic prefix, forexample, to maintain orthogonality between signals and/or to minimizeintercarrier interference. Tight synchronization may be difficult, forexample, in a system where a WTRU may be simultaneously connected tomultiple access points. Additional power reduction may be applied touplink transmissions, for example, to comply with spectral emissionrequirements for adjacent bands. Fragmented spectrum may be aggregatedfor WTRU transmissions.

OFDM (CP-OFDM) performance may be improved, for example, by morestringent RF requirements for implementations, such as operation using alarge amount of contiguous spectrum that might not require/useaggregation. A CP-based OFDM transmission scheme may provide a downlinkphysical layer for 5G similar to a 4G system with modifications to pilotsignal density and/or location.

5gFLEX radio access may be characterized by a very high degree ofspectrum flexibility that enables deployment in different frequencybands with different characteristics, which may include different duplexarrangements, different and/or variable sizes of available spectrum,such as contiguous and/or non-contiguous spectrum allocations in thesame or different bands. 5gFLEX radio access may support variable timingaspects, such as support for multiple TTI lengths and/or asynchronoustransmissions.

Multiple duplexing schemes (e.g., TDD, FDD) may be supported.Supplemental downlink operation may be supported, e.g., for FDDoperation, for example, using spectrum aggregation. FDD operation maysupport full-duplex FDD and/or half-duplex FDD operation. DL/ULallocation may be dynamic (e.g., might not be based on a fixed DL/ULframe configuration), e.g., for TDD operation. The length of a DL and/ora UL transmission interval may be set per transmission opportunity.

A WTRU may be configured to receive and/or detect one or more systemsignatures. A system signature may include a signal structure using asequence. A signal may be similar to a synchronization signal (SS),e.g., similar to LTE Primary Synchronization Signal (PSS) and/orSecondary Synchronization Signal (SSS). A signature may be specific to(e.g., may uniquely identify) a particular node (and/or TransmissionReception Point (TRP)) within a given area and/or it may be common to aplurality of nodes (and/or TRPs) within an area, which aspect might notbe known and/or relevant to a WTRU. A WTRU may determine and/or detect asystem signature sequence and/or may further determine one or moreparameters associated with the system. For example, a WTRU may furtherderive an index therefrom and/or may use the index to retrieveassociated parameters, e.g., within a table, such as an access table.For example, a WTRU may use received power associated with a signaturefor open-loop power control, e.g., to set an initial transmission powerwhen a WTRU determines that it may access (and/or transmit) usingapplicable resources of the system. For example, a WTRU may use thetiming of a received signature sequence, e.g., to set the timing of atransmission (e.g., a preamble on a PRACH resource) when the WTRUdetermines that it may access (and/or transmit) using applicableresources of the system.

A system signature may include any type of signal received by a WTRU forone or more purposes described herein.

A WTRU may be configured with a list of one or more entries. A list maybe referred to as an access table. A list may be indexed, e.g., where an(e.g., one or more, or each) entry may be associated with a systemsignature and/or to a sequence thereof. An access table may provideinitial access parameters for one or more areas. An (e.g., one or more,or each) entry may provide one or more parameters that may be useful forperforming an initial access to the system. Parameters may include atleast one of a set of one or more random access parameters (e.g.,including applicable physical layer resources, such as PRACH resources)in time and/or frequency, initial power level and/or physical layerresources for reception of a response. Parameters may (e.g., further)include access restrictions (e.g., PLMN identity and/or CSGinformation). Parameters may (e.g., further) include routing-relatedinformation, such as one or more applicable routing areas. An entry maybe associated with (and/or indexed by) a system signature. An such entrymay be common to a plurality of nodes (and/or TRPs). A WTRU may receivean access table, for example, via a transmission using dedicatedresources (e.g., by RRC configuration) and/or by a transmission usingbroadcast resources. In the latter case, the periodicity of thetransmission of an access table may be relatively long (e.g., up to10240 ms), which may be longer than the periodicity of the transmissionof a signature (e.g., in the range of 100 ms).

An access table may include any type of system information received by aWTRU for one or more purposes described herein.

A radio access network (RAN) slice may include one or more, or all,radio access network functions and/or transport network functions and/orresources, e.g., radio resources and/or backhaul/fronthaul resourcesalong with core network functions/resources that may be used and/orrequired to provide end-to-end services to a user. Network functionsmay, for example, be virtualized on a general-purpose processor, run asnetwork functions on specialized hardware and/or split betweenspecialized hardware and general purpose hardware. A PLMN may includeone or more network slices. A slice may be equivalent to an operator’ssingle, common and/or general purpose network. A RAN slice may includeone or more SOMs that may be optimized to support various services thatthe RAN slice may have to offer.

For example, WTRUs served within a slice may have, for example, one ormore of the following aspects in common: services and/or QoErequirements (e.g., ULLRC, eMBB, MMTC); WTRU categories (e.g., CAT 0 toM and/or beyond, additional categories may be defined for >6 GHz todifferentiate beamforming capability); coverage requirements (e.g.,normal coverage, enhanced coverage); one or more PLMN/Operators; supportfor specific Uu interface (e.g., LTE, LTE-Evo, 5G below 6Ghz, 5G above6Ghz, Unlicensed); and/or served by same core network slice. The terms“RAN slice” and “slice” may be used interchangeably.

Functions and/or components supporting an NR system may be logicallygrouped, for example, in terms of an Edge control/Access Plane (AP), aCentral Control Plane (CCP) and/or Central User Plane (CUP). Logicalgrouping may enable different components and/or functions of the systemto be isolated from each other. Isolation may enable components and/orfunctions to be controlled, configured, modified and/or operatedseparately from each other. Separation may be applied for componentsand/or functions associated with a specific WTRU, per TRP/NR-eNB, perTRPG, per TRPGs, per group of NR-eNBs, per LCH (and/or equivalent), perslice and/or the like. Further separation between centralized andaccess-related grouping may enable coordination between differentinstances of a function (e.g., system information provisioning, bearerconfiguration and/or equivalent) and/or between different instances ofdifferent functions (e.g., core network connectivity and/or userplane/bearer instances). An edge control function may be associated witha scheduler instance. A WTRU may be configured to associate a specificsignaling bearer and/or equivalent (e.g., a transport path/method) forcontrol of a MAC entity with the concerned MAC entity. A function mayuse the transport services of MAC protocols (e.g., as MAC ControlElements) and/or similar.

Central Control Functions (e.g., RAN central control functions) mayinclude functions, protocols and/or context that may be WTRU specificand/or applicable to one or more TRPs/edge control functions. A centralcontrol plane may be considered to be an anchor control function thatmay terminate the control interface towards the core network (e.g.,through the configuration/setup of routing paths and/or transport paths,which may, for example, be based on tuples configured for the WTRU). Acentral control function may include control functions related toselection of core network slice, CN-RAN interfaces, QoS management,security (e.g., master key management and/or key derivation, which maybe per group of TRPs/NR-eNBs), WTRU capability management and/or WTRUreachability within RAN.

Next generation air interfaces (e.g., including further evolution of LTEAdvanced Pro and/or a New Radio (NR)) may support a wide range of usecases with varying service requirements (e.g., low overhead and/or lowdata rate power efficient services (mMTC), ultra-reliable low latencyservices (URLLC) and/or high data rate mobile broadband services (eMBB))for diverse WTRU capabilities (e.g., low power and/or low bandwidthWTRUs, WTRUs capable of very wide bandwidth (e.g., 80Mhz), WTRU supportfor high frequencies (e.g., >6Ghz), etc.) under various mobilityscenarios (e.g., stationary/fixed, high speed trains, etc.) using anarchitecture that may be flexible enough to adapt to diverse deploymentscenarios (e.g., centralized, virtualized, distributed overideal/non-ideal backhaul, etc.).

Traffic models associated with next generation use cases may be expectedto be short and/or long bursts of data with varying inter-arrival timesfor data packets. A waiting period between consecutive data packets maybe referred to as an inactive period. Signaling associated with networkcontrolled mobility (e.g., measurement and/or handover) may beundesirable, for example, when inactive devices may be allowed to stayin connected mode. Signaling overhead associated with state transitionon an air interface and/or RAN-core interface may be undesirable, forexample, when an inactive device may be pushed to idle mode.

Low latency transition time between inactive and active states (e.g., inaddition to signaling reduction) may be implemented to meet controlplane latency requirements of next generation systems.

One or more procedures are described for light connectivity and/or WTRUautonomous mobility. A WTRU performing a state transition may includethe WTRU initiating a procedure that may lead to a change of state. Forexample, a WTRU performing a state transition to the CONNECTED state mayinclude the WTRU initiating a RRC procedure that may establish a new RRCconnection and/or that may re-establish, resume, and/or reconnect an RRCconnection (e.g., using an existing context and/or configuration). Astate transition may be autonomously initiated, event-triggered, and/orinitiated from the reception of signaling from the network, for example,based on one or more aspects of the WTRU’s configuration.

Procedures described herein may be applicable to different arrangementsof physical layer resources, different WTRU configurations, differentgroupings of applicable functions and/or other configurations and/orlogical functional grouping without restriction to examples describedherein.

Tracking areas may be modeled. A set of resources may be defined insupport of WTRU-autonomous mobility. The term of “tracking area” mayrefer to a logical group of transmission points (e.g., TRPs, eNBs, gNBs,and/or the like), logical group and/or arrangement of physical resourcesand/or cells. For example, a tracking area may be associated with a(e.g., single) control plane function and/or entity from the network’sperspective. For example, a WTRU may be tracked by the network at agranularity of a tracking area. For example, a tracking area may varydepending on the WTRU’s RRC state. For example, a logical group maydiffer for a WTRU in IDLE mode (e.g., MME-based tracking), in lightlyconnected state (e.g., RAN-based tracking) and/or in CONNECTED mode(e.g., eNB-based management).

Arrangements of physical resources may be modeled. A set of resourcesmay be identified, e.g., to support different WTRU behavior. The term“layer” may refer to an arrangement of (e.g., physical layer) resourcesassociated with a radio access network. An arrangement of resources maybe associated with one or more reference signal(s) and/or referencesignal processes such as those that may be used to determine an identityof such arrangement of resources.

For example, a layer may comprise one or more reference signal(s) (e.g.,received with transmit power above a certain threshold), one or morecell(s), one or more beam(s) and/or beam process(es). These may beassociated with one or more eNB(s), gNB(s), TRP(s), TRGP(s),signature(s), and/or carrier(s). Such terms may be used interchangeablyand/or equivalently herein unless stated otherwise.

A WTRU may be configured to operate using one or more layer(s). A singlelayer example may be a WTRU configured to operate using resourcesassociated with a macro cell. A multi-layer example may be a WTRUconfigured to operate using resources of a second layer associated withsmall/micro cells.

WTRU states may be modeled. A set of procedures and/or their respectiveinstances may be logically grouped and/or referred to as such. The terms‘state’ and ‘mode’ may be used interchangeably. Procedures describedherein may be applicable independent of state. A procedure may beapplicable for more than one state. A procedure described herein may beapplicable regardless whether states are actually defined.

The term “WTRU state” may be used to describe what specific set(s) offunctions and/or specific set of configuration aspects may be enabled(or not) at any given time.

A WTRU state may be realized, for example, as one or more of thefollowing: an RRC state for light connectivity; an RRC state combinedwith MAC state for a set of resources; and/or a behavior that may beindependent of RRC state.

An RRC state for light connectivity may be a state of a protocol, suchas a status of an L3/RRC protocol and/or may have configuration aspectsthat may determine the WTRU actions for an (e.g., any) event thathappens at a given time.

An RRC state combined with MAC state for a set of resources may be acombination of protocol states (e.g., a combination of RRC state and MACstate). For example, an RRC state may be a function of WTRU contextavailability in a network. An RRC state may reflect the status of WTRUconnectivity with a central control function. For example, a MAC statemay be a function of WTRU transmission status (e.g., a synchronizationaspect, the availability of specific resources and/or the like). A MACstate may reflect the status of WTRU connectivity with an edge controlfunction.

A behavior that may be independent of RRC state may be a configurationaspect. For example, a network may configure one or more rules that maydetermine a number of WTRU actions (e.g., in a specific scenario).Actions may be related to WTRU transition(s) between idle operation,light connected operation and/or fully connected operation.Transition(s) may be performed as a result of an RRC procedure, such asa reconfiguration.

A WTRU may operate, for example, according to one or more of thefollowing states and/or similar: idle mode; light connected/looselyconnected/Inactive mode; and/or connected/fully connected/Active mode.

A WTRU in idle mode (e.g., from the network’s perspective) might nothave a context with the radio access network. A WTRU might not have acontext at the edge control function and/or the central controlfunction, for example, in a distributed architecture. A WTRU may monitorpaging from the core network at a well-defined DRX cycle. A WTRU mayperform measurements and/or autonomous mobility. A WTRU may acquire,store and/or apply system information that may be valid for at leastidle mode operations.

A WTRU in light connected/loosely connected/Inactive mode and/or state(e.g., from the network’s perspective) may have a WTRU context stored inthe RAN. A RAN-core network connection may exist for the WTRU. A WTRUmay have context established at the central control function withlimited or no context at the edge control function, for example, in adistributed architecture. A WTRU may be tracked at a granularity of alogical area greater than or equal to a cell. A WTRU may be reached bythe RAN, for example, via paging message that may originate in the RANat DRX cycles that may be specific to the light connected state. It isunderstood that “light connected” and inactive may be usedinterchangeably herein.

A WTRU (e.g., from its own perspective) might not have an active and/orestablished connection to the RAN. Mobility in light connected state maybe WTRU controlled. A WTRU may move within a logical area withoutnotifying the network. A WTRU may notify the network when it determinesthat it has moved outside a logical area (e.g., the WTRU may fail todetect the signature/reference signal and/or another property that mayidentify the concerned area) and/or across a boundary between twodifferent logical areas (e.g., the WTRU may detect a different identityfor the current area). Mobility in light connected state may be networkcontrolled (e.g., to enable handover when data transfer may be allowedand/or ongoing).

A WTRU in connected/fully connected/active mode (e.g., from thenetwork’s perspective) may have connectivity with the network (e.g.,WTRU context may be established at the radio access network and/or aWTRU specific connection may be established between RAN and corenetwork). A WTRU may have context established at a central controlfunction and/or one or more edge control functions, for example, in adistributed architecture. One or more user plane functions/componentsmay be established for the WTRU. WTRU mobility may be tracked at celllevel. WTRU assisted, network controlled mobility may be permitted.Network configured, WTRU controlled mobility may be permitted.

A WTRU may be configured to support (e.g., specific) transmissionprocedures, such as connectionless transfers and/or similar.

A Connectionless transfer may be characterized by non-existence of aWTRU specific RAN-core network connection and/or absence of WTRU contextin the RAN. A WTRU may perform connectionless data transfers for datawithout having to establish an RRC connection at the radio accessnetwork, for example, by including context information in the data PDUsand/or by using default context. Context information may include WTRUidentity, flow/QoS information, routing information, security, etc. ARAN-core network interface may, for example, use a connectionlessinterface assisted by the context information in a (e.g., one or more,or each) data PDU and/or use a default tunnel/flow to exchangeconnectionless data for a WTRU

States described herein may represent a standalone/independent state,e.g., with transition logic in between states. States may haverelationships with each other. For example, a state may be realized as asubstate and/or as functional elements of another state, wheretransition between substates might not imply significantly different RRCfunction and/or might not trigger RRC behavior. For example, aconnectionless transfer may be realized as a substate and/or an accessmethod for a WTRU in idle and/or light connected state. For example, alight connected state may be seen as/interpreted as a RAN controlledstate.

A WTRU context may be modeled. A WTRU context may representshared/synchronized knowledge between a network and a WTRU regarding theWTRU’s capabilities, protocol states and/or parameters/configurationthat may be useful for operation of the WTRU. A WTRU context (e.g., froma network perspective) may be created at the RAN, for example, usinginformation from the core network, information obtained from the WTRU,information obtained from a peer RAN node and/or information created bythe RAN itself (e.g., during a connection establishment procedure and/ora reconfiguration of the WTRU).

A WTRU context may include, for example, one or more of the following:configuration aspect(s); protocol state aspect(s); and/or capabilitiesaspect(s).

Configuration aspect(s) may include, for example, one or moreidentities. An identity may refer to the WTRU’s context, to the WTRUitself and/or to a radio level identity (e.g., RNTI). An identity may beuseful to associate received control plane information (e.g., locationupdate for RAN-level tracking) with a proper WTRU context.

Configuration aspect(s) may include a measurement configuration. Ameasurement configuration may be useful, for example, when at least someaspects of the WTRU’s mobility may be network controlled.

Configuration aspect(s) may include a security context (e.g., securityalgorithm, applicable keys and/or sequencing information) associatedwith the WTRU. A security context may be useful, for example, whensecurity may be applied to control plane signaling (e.g., locationupdate for RAN-level tracking). A security context may be used whenresuming user plane data transmissions.

Configuration aspect(s) may include a configuration for logical QoSassociation/abstraction (e.g., bearer, flow, QoS profile, slice, etc.).This type of configuration may be useful, for example, to determine apriority level associated with downlink data arrival and/or to ascheduling request received by the WTRU. This type of configuration maybe used when resuming user plane data transmissions.

Configuration aspect(s) may include radio resource configuration. Aradio resource configuration may include configuration of transportand/or physical characteristics of transmission (e.g., transport channelconfiguration and/or physical channel configuration), configuration forpower control, feedback, beam configuration (e.g., beam process, beamsweeping, periodicity, beam mapping to physical resource), additionalspectrum resource (e.g., Scell), service specific configuration (e.g., acarrier may be associated with one or more, or a plurality of MACs,and/or one or more, or each, MAC for a service type), link supervisionconfiguration, RAN paging area configuration, plurality of DRX config(e.g., RAN level DRX, CN level DRX, service specific DRX, etc.). A radioresource configuration may be useful, for example, when a WTRUreconnects in a cell for which such configuration may be applicable(e.g., a cell in which the WTRU was previously active and/or a cell partof a group of cells with common configuration aspects).

Protocol state aspect(s) may include, for example, state variables,outstanding grants, semi-persistent grants, DRX state, pendingtransmissions/retransmissions/feedback/triggers (e.g., polls, statusreports), status of buffers (e.g., ARQ buffer, HARQ buffer, discardbuffer), security context, header compression context, status of timers(e.g., running, expired, stopped). Protocol state aspect(s) may beuseful, for example, when a WTRU reconnects in a cell for which suchstate may still be applicable (e.g., a cell in which the WTRU waspreviously active and/or a cell part of a group of cells with commonprotocol instances towards a given WTRU).

Capabilities aspect(s) may include, for example, transport capability ofthe WTRU (e.g., maximum number of bits/transport blocks that a WTRU maytransmit/receive within a time interval), beamforming capability, numberof RF chains, number of antennas, security capability, support ofsimultaneous services (e.g., eMBB and/or URLLC), capability to connectto multiple transmitting points, supported bands, supported maximumbandwidth, supported TTIs, minimum time between data reception andfeedback, etc. Capabilities aspect(s) may be useful, for example, when aWTRU reconnects to the radio access but may require/use reconfigurationfor at least one aspect.

Handling a WTRU context (e.g., from a network perspective) may be afunction of deployment and/or RAN architecture. For example, anarchitecture may include an edge control function and/or a centralcontrol function within the radio access network. A WTRU context may bedistributed across different entities. A configuration that mayrequire/use low latency and/or tight coupling to the transmission point(e.g., control of beam configuration/update) may be provided by the edgecontrol function. A configuration that may require/use coordinationbetween multiple transmission points may be provided by the centralcontrol function. A WTRU context related protocol status may be splitbetween edge control and central control function. For example, acentral control function may maintain an RRC protocol context, aflow/bearer split function, a reordering protocol state, a headercompression state and/or a security context while an edge controlfunction may maintain a beam process context, a layer 1 context, a HARQcontext, etc.

A WTRU context may be dynamically placed between edge and centralcontrol functions. A placement may be specific to a WTRU, to aservice/slice/flow, to a transmission point and/or to a central controlfunction. A WTRU context (and/or portions thereof) may be stored atmultiple locations. For example, context may be stored at the servingedge control function and/or at potential target edge control functions,e.g., to enable faster mobility. A clean separation of control and/oruser functions may be provided, for example, where a WTRU may receiveconfiguration for signaling flow from an entity different than entitythat provides configuration for data flow.

Handling of a WTRU context may be a function of WTRU state. For example,handling of a WTRU context for a connected WTRU may be controlled by anetwork command (e.g., in a reconfiguration message, mobility command,etc.). For example, a WTRU may determine what part of a WTRU contextsurvives a change of cell (and/or equivalent), e.g., as the outcome of aWTRU-autonomous procedure when in light connected state. For example, aWTRU may retain WTRU layer 2 state based on data transmission capabilityin light connected state (e.g., whether data transmission may be allowedin light connected state or not), for example, in case the WTRU may moveto connected state for data transmission. A WTRU may complete theongoing data transmission before going to light connected state, forexample, when data transmission might not be allowed in light connectedstate. RLC may deliver the buffered (e.g., out of sequence SDUs) toPDCP, for example, when a WTRU enters a light connected state.

Control plane aspects of light connectivity may be provided. Lightconnectivity related functionalities and/or configurations may beprovided. A transition may occur from light connectivity state to anactive state (e.g., connected state).

A WTRU may enable a set of functions (e.g., after a well-defined periodof inactivity), for example, when the WTRU determines its location to bewithin a logical area where the received light connectivityconfiguration may be valid.

A set of functions may correspond to state transition, e.g., transitionto light connected state. A set of functions may perform operationscorresponding to light connectivity (e.g., applying radio resourceconfiguration applicable for light connectivity, performing measurementsconfigured for light connectivity, monitoring a paging channelcorresponding to light connected state, suspending data transmissions onthe uplink, performing ran paging area updates, etc.)

A period of inactivity may correspond to absence or low volume of DLand/or UL data transmission for a duration greater than a preconfiguredtime duration, e.g., in terms of subframes, TTIs, DRX cycles, etc.Inactivity may be characterized by absence of grants, not enough grantsand/or a reception of valid grants without data to transmit.

Location within a logical area may be determined as a function of ameasured reference signal signature associated with a logical areaand/or may be determined by reception of a broadcast identity associatedwith the logical area.

A WTRU may perform state transition as a function of asignature-specific measurement threshold. Thresholds may vary dependingon active service(s), such as the most stringent service at the time theWTRU received the light connectivity configuration. One or more, or aplurality, of reference signals and/or associated thresholds may beconfigured. A (e.g., one or more, or each) reference signal may beassociated with a different part and/or parts of a radio resourceconfiguration. A WTRU may activate configuration and/or parts ofconfiguration, for example, based on associated signature-specificmeasurements.

A WTRU may implicitly transition to a light connectivity state. A WTRUin connected mode/state may initiate transition to light connectivity. Atransition may be implicit (e.g., it might not involve signaling to thenetwork). A WTRU and a network may pre-agree on and/or preconfigure setof rules for implicit transition to light connectivity. A WTRU in aconnected state may receive and/or store configuration aspects relatedto light connectivity. A WTRU may move to light connected state and/oractivate the stored light connectivity configuration based on one ormore rules. Examples of triggers for moving to and/or from a lightconnected state and/or INACTIVE state may include one or more of aperiod of inactivity, a transmission/reception of a volume of datatransmission, occurrence of a configured behavior, activating and/ordeactivating one or more services, etc.

An implicit transition may be based on a period of inactivity. A WTRUmay be configured to enter light connectivity based on activity levelsduring connected mode. For example a WTRU (e.g., during connected DRX)may keep track of number of consecutive DRX cycles during which therewas no DL and/or UL data transmission activity. A WTRU may enter lightconnected mode, for example, when there was no data transmissionactivity for n consecutive DRX cycles. A WTRU may be configured with aninactivity timer that may be (re)started whenever the UL and/or DL dataactivity may be completed. A WTRU may trigger entry to light connectedmode, for example, when the value of an inactivity timer may be above athreshold.

An implicit transition may be based on a volume of data transmission. AWTRU may keep track of the volume of data (e.g., number of bytes and/orpackets) transmitted over a predefined time interval. A WTRU may triggerentry to light connected mode, for example, when the data volume may bebelow a predefined threshold.

An implicit transition may be based on a configured behavior. A WTRU may(e.g., always) enter light connected state as a default state uponreceiving a connection release message. A connection release message mayor might not have an explicit indication for light connectivity. A WTRUmay leave a light connected state, for example, when the WTRU leaves thecell and/or a validity timer expires, for example whichever may occurfirst.

An implicit transition may be based on active services. A transition mayoccur, for example, based on a combination of one or more other rulesand/or active services at the WTRU. For example, a WTRU may enter lightconnectivity when MTC services may be active and/or when volume of datatransmission may be below a predefined threshold. A WTRU might not enterlight connected state, for example, when volume of data transmission maybe low and/or when for example a URLLC service may be active.

An implicit transition may be a function of a subscription profile. Forexample, a WTRU may enter light connected state based on a configurationfrom a core network. For example, a configuration may be based on a WTRUsubscription. A WTRU may receive a configuration, for example, in aregistration response message and/or an attach accept message.

An implicit transition may be a function of time of day. For example, aWTRU may enter light connected state based on a time of dayconfiguration from the core network. For example, a WTRU may receive aconfiguration to allow the use of a light connected state during aspecific time period. For example, a WTRU may receive a configurationwith an indication to allow the use of light connected state when theWTRU may be operating in low activity mode for a period (e.g., anend-user may configure a “do not disturb mode” period and/or a “nightmode” period).

An implicit transition may be a function of power saving. For example, aWTRU may enter a light connected state based on a WTRU battery leveland/or power saving settings. For example, a WTRU may enter lightconnected state when a battery level may be below a certain threshold.For example, a WTRU may enter light connected state based on a powersaving settings/preferences (e.g., a WTRU may prioritize using lightconnected state for data transfers when configured to save power whilethe WTRU may prefer transitioning to a CONNECTED mode to maximizeperformance).

An implicit transition may be a function of WTRU capability. Forexample, a (e.g., low cost) WTRU may operate (e.g., only) in a lightconnected state and/or might not support a fully connected state and/orone or more functions associated with a fully connected state. Forexample, a WTRU may perform data transfer while staying in lightconnected state.

A network may initiate a light connectivity state. A WTRU in connectedmode/state may transition to light connected mode, for example, based ona received network command. A WTRU may consider a received networkcommand valid, for example, (e.g., only) when a valid security contextmay exist in the WTRU. A WTRU may perform actions as if an invalidconfiguration may be received, for example, when there is not a validsecurity context associated with a command. A WTRU may receive a networkcommand via (e.g., a field in) a layer 3 message.

A command may be signaled in a variety of ways. For example, a commandmay be signaled by an RRC connection release with explicit indicationfor light connectivity (e.g., ReleaseCause as ‘light connectivitysetup’).

A command may be signaled by an RRC connection reconfiguration withexplicit state indication as light connectivity. A WTRU may infer alight connectivity indication from one or more aspects of RRC connectionreconfiguration, which may include presence of a configuration specificto light connected mode, e.g., RAN PA configuration, DRX/pagingconfiguration specific to light connected mode, a WTRU ID to use inlight connected mode and/or absence of a configuration that may berequired/used for fully connected operation (e.g., dedicated physicalchannel configuration).

A command may be signaled by an RRC connection reconfiguration withmobility control information and/or state control information. Forexample, a WTRU may receive a handover command to a target cell alongwith state indication and/or a handover to a RAN PA. A WTRU may choose abest cell in a specified RAN PA. A WTRU may move to a target cell and/ormay perform actions specified for entry to light connected state.

A command may be signaled by a dedicated RRC light connection setupmessage, which may include configuration aspects that may be specific tolight connected mode. A WTRU may move from connected state to lightconnected in the same cell/transmission point.

A WTRU may receive a network command via layer 2 and/or layer 1indication, such as one or more of the following: a MAC control elementand/or a reserved logical channel ID; a DRX command that may activate aDRX configuration that may be specific to light connected mode; and/or aDCI message and/or PDCCH order to enter light connectivity.

For example, the WTRU may initiate a transition to a light connectivitystate after one or more, or each, of the ongoing HARQ processes are, orbecome, inactive. For example, the HARQ processes may have completedsuccessfully and/or may be HARQ processes that are suspended/paused. Thedetermination that HARQ processes are complete/inactive may be adetermination based on reception of HARQ ACK (and/or infernal thereof)and/or based on a received DCI.

For example, the WTRU may initiate a transition to a light connectivitystate when there are no outstanding/pending RLC PDU(s) and/or segmentthereof in the WTRU buffer. For example, the determination may be basedon the DRBs and/or LCH and/or equivalent and/or based on certain DRBs,such as for example DRBs that remains configured for light connectivityoperation.

A WTRU may transition to light connectivity state from an inactivestate, which may correspond to RRC IDLE mode. A WTRU may support atransition from an inactive state to a light connected state.

A transition from inactive to light connectivity may be useful for asystem supporting low latency and/or reduced signaling (e.g., for sparsedata transfers from idle mode). A transition may reduce signalingoverhead and/or latency/delays that may otherwise occur before a WTRUmay perform a first transmission, for example, when they may besupported in a light connected state. A first transmission may includecontrol plane messaging (e.g., to establish/resume an RRC connection). Afirst transmission may include MAC control information and/or similar(e.g., to indicate a use for further transmission resources). A WTRUwith infrequent data transfers may utilize light connectivity instead offull connection, for example, when user plane data transfers may besupported in light connected state.

A transition from inactive to light connectivity may be useful for asystem supporting idle mode for power on and/or light connectivity forinactive otherwise. A transition may be required/useful for a WTRU thatpowers on, performs IDLE mode procedures and/or an initial access (e.g.,for registration to the network) and/or receives an indication totransit to a light connected state.

For example, a WTRU may indicate a request to move to a lightconnectivity state when it accesses the system (e.g., based on itscapability and/or its type of service). A network may redirect a WTRU tolight connected state, for example, based on a WTRU connection request.

DL paging may contain an explicit indication to push a WTRU to lightconnected state. For example, a network may (e.g., when mobileterminated services require/use low latency) proactively pre-configure acontext for a WTRU and/or may provide indication in a paging message.

A WTRU may perform one or more actions upon entering light connectivitystate. A WTRU may (e.g., upon entering light connected state) apply aradio resource configuration. A WTRU may (e.g., upon entering lightconnected state) start a validity timer that may be associated with alight connectivity operation/state. A WTRU may restart a timer, forexample, upon reception and/or transmission of control signaling,control plane data (e.g., when user plane transmissions might not besupported in such state) and/or user plane data (e.g., when user planetransmission may be supported). Control information may be an areaupdate message for the purpose of RAN-based paging. A WTRU may (e.g.,upon timer expiration) determine that one or more aspects of the WTRU’sconfiguration may be no longer valid. A WTRU may initiate a transitionto a different state such as IDLE mode, for example, when the WTRU(e.g., further) determines that it has been inactive for some time. Atimer-based action may be useful, for example, to enable a transitionaway from the light connected state without control signaling overheadwhen there may be a prolonged period of inactivity. For example, a WTRUmay initiate a transition to a different state such as connected mode. AWTRU may receive a reconfiguration (e.g., for connected mode operationand/or for returning to light connected mode) and/or may update a newlyinvalidated configuration, which may be useful as a safeguard to avoidWTRU and/or network loss of synchronization in terms of reachability.

A WTRU may (e.g., upon entering light connected state) start a validitytimer with common and/or dedicated resources associated with lightconnectivity, e.g., when configured. For example, a WTRU’s associatedbehavior may be similar to the foregoing description.

A WTRU may (e.g., upon entering light connected state) stop monitoringan (e.g., any) applicable dedicated control channel(s) (e.g., withC-RNTI and/or equivalent), for example, when data transfer might not beallowed during light connected state and/or when a shared channel may beused for initiating a data transfer.

A WTRU may (e.g., upon entering light connected state) performdiscontinuous reception according to a DRX cycle specific to lightconnected state.

A WTRU may (e.g., upon entering light connected state) monitor RANpaging specific to a RAN Paging area.

A WTRU may (e.g., upon entering light connected state) start a periodicRAN Paging area update timer. For example, a WTRU’s behavior associatedwith a timer may be similar to other timers described herein and/or maybe restarted, for example, when the WTRU successfully completes thelocation update procedure for the RAN-controlled paging. A WTRU mayperform a location update procedure upon expiration of a timer, whichmay be useful as a safeguard to avoid WTRU and/or network loss ofsynchronization in terms of reachability.

A WTRU in light connected state may perform one or more actions.

A WTRU (e.g., in light connected state) may start performingmeasurements applicable for light connectivity.

A WTRU (e.g., in light connected state) may perform network configured,WTRU controlled mobility.

A WTRU may (e.g., when a validity timer expires) perform actionsconsistent with leaving light connectivity. A WTRU may (e.g., when inlight connected state) restart a validity timer based on one or moreconditions when data transfer may be allowed during light connectivity,such as when a WTRU receives RAN paging for DL data arrival and/or whena WTRU receives DL and/or UL grant for data transmission. A WTRU may(e.g., when in light connected state) restart a validity timer based onone or more conditions when data transfer might not be allowed duringlight connectivity, such as when a number of cell changes and/or RANupdates over a predefined time window may be below a preconfiguredthreshold.

A WTRU (e.g., in light connected state) may perform a RAN Paging areaupdate and/or may perform other actions permitted during lightconnectivity.

A WTRU (e.g., in light connected state) might not (e.g., perhaps whensystem information applicable for RAN paging area may be configured)perform one or more of: acquire system information upon cell changewithin RAN Paging area; and/or monitor SI-RNTI and/or paging for systeminformation update. This may be useful, for example, when a WTRUreceives a notification of a change in system information and/or anychange in applicable system information (e.g., using RAN-based pagingand/or dedicated signaling).

A WTRU (e.g., in light connected state) may (e.g., when systeminformation applicable for RAN paging area might not be configuredand/or when a WTRU may determine a change of system information for acell (and/or equivalent) that a WTRU may be camping on) perform one ormore of the following: detect and/or acquire system information viaperiodic and/or on-demand methods; and/or monitor a paging channel,e.g., according to its idle mode DRX cycle for possible systeminformation update.

A WTRU (e.g., in a light connected state) may monitor a change inlocation and/or may perform one or more other actions permitted in alight connected state, for example, based on reselecting to one or moreof: a cell in the same RAN Paging area; a cell in a different RAN Pagingarea; a cell in a different Tracking area; and/or a cell not supportinglight connectivity.

A WTRU in light connected state may perform different levels of datatransfer supported for light connected mode.

Radio resources may be configured for light connectivity mode. A lightconnectivity configuration for a WTRU may include a radio resourceconfiguration and/or aspects related to RAN paging (e.g., paging channelconfiguration, DRX configuration, and/or RAN PA configuration, and/orassociated timers).

A WTRU in light connected state may be associated with an identityassigned by the RAN. An identity may be unique with a RAN Paging area.An identity may be unique for a given set of physical resources withinan applicable RAN Paging area. For example, resources may correspond toa RAN-paging channel, to a control channel associated therewith and/oran aspect of a channel (e.g., a specific P-RNTI), to physical resourcesin time, to physical resources in frequency and/or to physical resourcesassociated with a specific numerology. A type of multiplexing may beuseful to scale the number of WTRUs that may be in a state for a givenRAN Paging area, for example, in terms of paging load and/or in terms oftype of service (e.g., low latency VS best-effort traffic for sparseintermittent user plane data). For example, a cell may support multipleinstances of a RAN-based paging channel whereby different WTRUs maymonitor different paging messages. An instance may be differentiatedbased on at least one the aforementioned aspects.

A WTRU identity may uniquely identify a context associated with a lightconnected WTRU. For example, a WTRU may receive an identity in areconfiguration message that may configure light connectivity. Forexample, an identity may be a combination of an identity of the cell(e.g., a PCell) where light connectivity may have been (e.g., first)configured and/or the C-RNTI that may have been used (e.g., just beforeentering light connected state for that cell). For example, a WTRUidentity may be assigned by a RAN control function that may store/handleWTRU context during light connectivity. A WTRU identity may be assignedby a central control function, for example, in a distributedarchitecture with an edge control function and/or a central controlfunction.

A WTRU may consider a light connectivity configuration to be valid for aplurality of cells under the same RAN paging area. A WTRU may consider alight connectivity configuration to be valid for (e.g., one or more, orall) cells that may be part of a RAN paging area (RAN PA). Validity mayapply to multiple (e.g., one or more, or all) RAN paging areas that maybe included in a WTRU’s configuration. A WTRU may receive systeminformation for a plurality of cells under the (e.g., same) RAN pagingarea, e.g., as a part of a light connectivity configuration.

A WTRU may (e.g., upon entering light connected state) apply a radioresource configuration, with or without an order.

A WTRU (e.g., when it was in connected state before entering lightconnected state) may (e.g., first) deactivate/remove/deleteconfigurations that may be no longer applicable in light connectedstate. For example, the WTRU may deactivate one or more of the Scells,PScells, etc. The WTRU may consider remaining configuration from aconnected state as a baseline configuration. The WTRU may (e.g., then)apply and/or overwrite a radio resource configuration that may bereceived via a command that triggered light connectivity. The WTRU(e.g., when one or more parameters might not be configured) may applythe common configuration from the system information that may beapplicable for the whole RAN PA. The WTRU may acquire and/or apply abroadcast configuration from system information applicable for thecurrent cell.

For example, one or more aspects of a configuration for lightconnectivity may be received using differential coding, whereby zero ormore existing configuration parameters may retain the current value(e.g., in case the parameters might not be present in thereconfiguration message and/or the parameter may be applicable in lightconnectivity), zero or more existing configuration parameters may beupdated (e.g., in case the parameters may be present in thereconfiguration message and/or zero or more configuration parameters maybe configured, such as parameters that may be specific to the lightconnectivity state).

A default configuration may be predefined for a light connected state. Adefault configuration may be common to multiple (e.g., one or more, orall) WTRUs in a cell and/or in a RAN paging area.

A WTRU may update one or more aspects of stored configuration (e.g.,including a radio resource configuration) that may be associated with alight connectivity state, for example, according to one or more of thefollowing: based on a response received in association with a RAN PAupdate procedure; and/or based on cell specific information.

A response may be received in association with a RAN PA updateprocedure. A WTRU may trigger a RAN PA update, for example, when astored configuration may no longer be applied in a cell (e.g., when astored configuration violates/mismatches with a common configurationbroadcast in a cell). This may happen, for example, when a controlchannel configuration/RAN paging configuration for a light connectivitystate may be different from a broadcast configuration in a cell. A WTRUmay set the cause in the RAN PA update indicating incompatible lightconnectivity configuration. A WTRU may store and/or apply a modifiedlight connectivity configuration from a received RAN PA update responsemessage.

Cell specific information may be available. A WTRU may use a storedconfiguration (e.g., provided at the time of entry to lightconnectivity) as a baseline and/or may update/overwrite parts of thestored configuration, e.g., according to access/broadcast information ina new cell. For example, a WTRU may update configuration related to aninitial access configuration, for example, when the WTRU moves from onecell to another.

A WTRU may update a radio resource configuration associated with aconnected state (e.g., from a received reconfiguration message), forexample, when transitioning from light connected state to a connectedstate. Reconfiguration may include admission control aspects. Forexample, a WTRU may resume (e.g., only) a subset of bearers that mayhave been inactive during a light connected state.

A WTRU may be reachable during a light connectivity state. A RAN PagingArea (RAN PA) may be conceptually defined as a logical area composed ofone or more transmission points (e.g., TRPs, TRPGs) and/or a logicalabstraction thereof (e.g., one or more cells).

A RAN paging area may be applicable to a WTRU in light connected state.WTRU actions in a light connected state and/or INACTIVE state may be afunction of, for example, the WTRU’s location, reference signalmeasurement(s) associated with RAN paging area and/or WTRU contextstored in the network. A RAN paging area may be associated with a radioresource configuration that may be preconfigured and/or stored. A WTRUmay activate/apply different parts of a stored/received configuration,for example, when measurements of a reference signal associated with aRAN paging area may be above a predefined threshold.

A RAN Paging area may be materialized, for example, by a measurement ofa system signature and/or reference signal. A (e.g., one or more, oreach) RAN paging area may associated with a (e.g., unique) systemsignature and/or reference signal. A WTRU may consider its location tobe within a RAN paging area, for example, when a measurement of areference signal and/or system signature associated with the RAN pagingarea may be above a threshold. A WTRU may determine a relationshipbetween a transmission point and a RAN paging area, for example, basedon measurements of a reference signal. For example, a (e.g., one ormore, or each) RAN paging area may be associated with a base referencesignal (e.g., a Zadoff-Chu (ZC) sequence). Transmission points withinthe same RAN paging area may use a cyclic shift of a base referencesignal associated the RAN PA.

A RAN paging area may be a function of cell ID by broadcast signaling. AWTRU may determine a RAN paging area, for example, based on a logicalidentifier that may be transmitted as a part of cell ID. For example,part of cell ID may indicate the identity of a RAN paging area. Forexample, a cell ID may be N bits. The most significant M bits mayindicate the RAN paging area and/or (N-M) bits may indicate the identityof the cell within the RAN paging area.

For example, a group of cells and/or transmission points belonging tothe same RAN paging area may be indicated as an explicit list of cellIDs. A WTRU may receive the list of cell IDs in a system informationbroadcast.

A (e.g., one or more, or each) RAN paging area may be associated with an(e.g., a unique) identifier. A WTRU may receive a broadcast signaling inMIB and/or SIB with (e.g., unique) logical identity associated with aRAN paging area.

A RAN paging area may be materialized, for example, by connectivity to acontrol function. A WTRU may determine a RAN paging area as a functionof reachability and/or connectivity to a control function. For example,a WTRU may determine its location to be within a RAN paging area, forexample, when it may reach the RAN control function associated with theRAN paging area. For example, a WTRU may determine a change in RANpaging area, for example, when there may be a change in RAN controlfunction and/or core control function.

A RAN paging area may be materialized, for example, by specificarrangement of physical resources. For example, a WTRU may determinethat a carrier and/or frequency on which it may be operating on may bepart of a RAN PA based on detection and/or reception of a signal. Asignal may be a reference signal (e.g., PSS/SSS, NR-SS) and/or a channelstate information-reference signal (e.g., CSI-RS). A signal may be asignature (e.g., a system signature). A signal may provide an identity(e.g., a cell/TRP/TRPG identity and/or an identity for a group thereof).For example, a WTRU’s configuration may include one or more identitiesfor a (e.g., one or more, or each) RAN PA applicable to the concernedWTRU in light connectivity. An identity may provide an identity of a RANPA itself. A signal may be a general signal (e.g., a PositioningReference Signal (PRS)) and/or a signal dedicated to this purpose.

For example, a WTRU’s configuration may include a list of one or moreidentities for RAN PAs applicable to the concerned WTRU in lightconnectivity. A WTRU may receive a signal for the concernedcarrier/frequency that may be used for monitoring RAN-based paging(e.g., a direct association between RAN PA and physical resources suchas for RAN-based paging) and/or for a different carrier/frequency (e.g.,an indirect association based on geo-location such as under the coverageof a macro cell while being reachable in other frequencies). Receiving asignal for a different carrier/frequency may result in fewer broadcastsignals in the operating frequencies, which may result in providingadditional resources in a RAN PA area that matches a macro celldeployment. Receiving a signal for the concerned carrier/frequency mayprovide more flexibility, e.g., in terms of definition and/or deploymentof RAN PA areas.

A RAN Paging area may be specific to a WTRU and/or service/slice. A RANpaging area configuration may be flexible and/or may be adapted fordiverse deployment scenarios and/or to meet different requirements. Forexample, a size of RAN paging area may be adjusted, e.g., to tradeoffbetween signaling overhead for paging and/or WTRU power consumption dueto frequent RAN paging area updates.

A WTRU may be configured with one or more RAN Pas. Area definitions(e.g., in terms of cell identities for one or more, or each, area) maybe provided to a WTRU, e.g., using dedicated signaling. A networkimplementation may determine whether (e.g., one or more, or all) WTRUsmay be configured with same or different set of areas and/or withsimilar areas (e.g., in terms of cell identities for one or more, oreach, area).

A RAN paging area may be WTRU specific. For example, a WTRU that may bestationary or with low mobility may be assigned a smaller RAN pagingarea while a WTRU with medium/high mobility may be configured with alarger RAN paging area.

A RAN paging area may be service/slice specific. For example, a WTRUthat may support a (e.g., specific) service (e.g., URLLC and/or similar)and/or that may be configured with at least one bearer associated withthe service may be configured with a specific and/or smaller RAN pagingarea that may include (e.g., only) cells/TRPs/TRPGs with suitablesupport for the requirements of concerned service(s). For example, aWTRU that may support a generic data transfer service (e.g., an eMBBservice) may be configured with a different (e.g., larger) paging area.A RAN paging area may (e.g., similarly) be slice specific. A WTRUconnected to multiple slices/services may, for example, consider thesmallest RAN paging area among the active services/slices as theconfigured RAN paging area.

A WTRU may be configured so that a specific TRP/TRPG/eNB/cell may beassociated with more than one RAN paging area. A WTRU may be (e.g.,concurrently) configured with multiple RAN paging areas, where one ormore, or each, may be associated with a different service and/or bearertype.

A RAN paging area may be applicable to a WTRU in a light connected stateand/or may be characterized by one or more of the following.

A WTRU may support WTRU-autonomous mobility. For example, a WTRU maymove between cells (and/or similar) in a RAN paging area, e.g., withoutnotifying the network. Mobility and/or area may be network controlledbased on configuration.

A WTRU may apply a DRX cycle and/or may determine paging occasions forRAN-based paging that may be specific to a (e.g., one or more, or each)RAN paging area and/or WTRU-specific (e.g., for load distribution).

A WTRU may have a paging channel configuration specific to a RAN pagingarea. A RAN paging area may include resources with one or moreoperational parameters that may have common characteristics (e.g.,numerology, bandwidth, control channel configuration, and/or systeminformation).

Support may be provided for service continuity. A WTRU in a lightconnected state may be reached by the network, for example, at a RAN PAgranularity. A WTRU may (e.g., be required to) monitor a paging areachange during WTRU autonomous cell changes. A WTRU may determine achange in paging area, for example, based on a (e.g., specific)realization of a RAN PA. For example, a WTRU may perform a determinationbased on measurements of a reference signal, a change in broadcastsignaling and/or a change in connectivity control function. A WTRU may(e.g., upon detecting a change in a RAN paging area) perform a RANpaging area update procedure.

One or more RAN PA update procedures may be provided. One or moreprocedures may be triggered. A WTRU may initiate one or more RAN PAupdate procedures, for example, according to one or more of thefollowing (e.g., triggers): a determination of change in a RAN PA area;an expiration of a periodic RAN PA update timer; upon receiving a RANpaging message with a RAN PA update trigger; a change in RAN PAconfiguration; detecting WTRU entrance into an NR cell from an LTE cellin a light connected state; detecting WTRU entrance into an LTE cellfrom an NR cell in light connected state; and/or performing a RAN PAupdate procedure at the WTRU. A WTRU may perform a RAN PA updateprocedure by one or more of: using data transfer mechanisms (e.g., whilestaying in the inactive state); performing a reconnection and/or resumeprocedure (for example, the reconnection and/or resume procedure mayexplicitly and/or implicitly indicate the RAN PA update from the WTRU;the WTRU may include one or more of: a WTRU identity, a source cell ID,and/or an identity of previous RAN area, etc. in the resume and/orreconnection message) perhaps for example when a RAN PA update isinitiated; performing a RAN PA update in combination with a trackingarea update procedure; and/or initiating a connection (re-)establishment(and/or equivalent) for the purpose of performing a RAN PA update.

A WTRU may take action after the reception of a RAN PA update response.A WTRU may transmit a RAN Paging Area update message. The WTRU maymonitor the control channel (e.g., for a predefined time) for a RAN PAupdate response. A RAN PA update response message may, for example,include one or more of the following: common/dedicated resources forlight connectivity, which may be valid for a short time and/or valid aslong as the signature sequence/reference signal associated with theserving cell remains above a threshold; reconfiguration of a storedlight connectivity configuration (e.g., possible change in DRX/pagingchannel configuration and/or update (such as, for example, updatedsecurity configurations (e.g., Nexthop Chaining Counter (NCC))));dedicated system information, which may be valid over the entire RANpaging area; an indication to transition to a different state (e.g., toIDLE and/or CONNECTED mode and/or state); and/or an indication to remainin the current state (e.g., LIGHT CONNECTED mode).

An indication may be implicit and/or explicit. An indication may becombined with a timer value. A WTRU may start a timer using the receivedvalue and/or may perform further actions upon expiration of the timervalue. A WTRU may (e.g., for data transfers associated with the servicesfor which light connectivity is applicable), for example, restart atimer upon (e.g., successful) completion of the RAN paging areaprocedure and/or upon successful data transmission and/or reception. Forexample, a WTRU may initiate a transition to IDLE mode upon expirationof a timer. For example, a WTRU may initiate a RAN paging update uponexpiration of a timer.

A relation may exist and/or may be created between a RAN Paging Area(PA) and a Tracking Area (TA). A geographical region corresponding to atracking area and/or a list of tracking areas may be associated with thesame logical core control plane function (e.g., a MME). A geographicalregion may correspond to one or more logical RAN Paging areas. A RANpaging area may be smaller or equal to a tracking area. A (e.g., single)RAN paging area may be mapped to one or more tracking areas and/orlist(s) of tracking areas associated with a (e.g., single) core controlplane function. A tracking area may be defined in terms of a group ofRAN paging areas.

A WTRU may perform an area monitoring procedure while in light connectedstate. An area monitoring procedure may involve, for example,determining a WTRU location in terms of cell granularity, RAN pagingarea granularity and/or tracking area granularity. A WTRU may performdifferent actions, for example, based on a change in RAN paging area(e.g., only) and/or a change in RAN paging area and/or tracking area.For example, an area monitoring procedure may be executed on a (e.g.,one or more, or each) cell change and/or a configuration update that mayaffect a RAN paging area and/or tracking area.

A WTRU may consider light connectivity to be valid within a RAN pagingarea and/or across multiple RAN paging areas, for example, when the RANpaging areas may belong to the same tracking area and/or core controlfunction. A WTRU may exit light connectivity and/or may perform atracking area update, for example, upon reselecting a cell that maybelong to a tracking area different than the tracking area where thelight connectivity may have been configured.

A WTRU in light connectivity may (e.g., upon entering a new trackingarea under the same core control function) perform a joint RAN pagingarea update and tracking area update. A WTRU may transmit an RRC message(e.g., a RAN Paging area Update message) that may be piggybacked with aNAS message (e.g., Tracking area update). A WTRU may trigger (e.g.,only) a tracking and/or paging area update, which may act as an implicitRAN paging area update.

A WTRU may take actions that may be related to RAN paging area handling.A WTRU may monitor notification(s) and/or paging from a RAN, forexample, while in light connected state.

A WTRU may determine RAN paging channel resources. A WTRU may determinedownlink (DL) resources that may be used to receive a RAN pagingmessage, for example, based on a DL grant in a subset of control channelresources. For example, a WTRU may monitor a (e.g., specific)time/frequency region that may be associated with a downlink controlchannel for a (e.g., possible) RAN paging message. For example, a WTRUmay be configured with a cell specific subset of control channelresources. For example, a WTRU may be configured with a subset ofcontrol channel resources that may be common to a RAN paging area.

A WTRU may monitor DL grants associated with a predefined and/orpreconfigured RNTI (e.g., RANP-RNTI) for receiving RAN paging messages.

For example, a RANP-RNTI may be a predefined constant associated with aRAN paging message. For example, RANP-RNTI may take a predefined value(e.g., 0xFFFC).

For example, a RANP-RNTI may be specific to a WTRU and/or a group ofWTRUs. For example, a WTRU may receive an assignment of RANP-RNTI, e.g.,upon entering light connected state and/or as a part of on-demand systeminformation.

For example, a RANP-RNTI may be specific to a RAN paging area. Forexample, a RANP-RNTI may be a function of system signature that may beassociated with a RAN paging area.

For example, a RANP-RNTI may be specific to a service. For example, aWTRU with MTC traffic may be associated with a RANP-RNTI, which may bedifferent from a WTRU with URLLC traffic. This may reduce powerconsumption (e.g., MTC devices may be transparent to frequent RAN pagingfor URLLC service).

A WTRU may be configured with an isolation mechanism, for example, toreceive RAN paging messages and/or legacy paging messages. Isolation mayreduce unnecessary overhead for a WTRU to receive and/or decode pagingmessages that might not be relevant to its operation and/or state.

For example, isolation may be achieved in terms of (e.g., based on)RNTI. A WTRU may monitor RANP-RNTI (e.g., to monitor RAN pagingmessages) and/or may monitor legacy P-RNTI (e.g., to monitor legacyand/or core network paging messages).

For example, isolation may be achieved in terms of (e.g., based on)time/frequency resources. A WTRU may be configured with overlappingand/or non-overlapping paging occasion for RAN paging and/or legacypaging.

A WTRU may be configured with an alignment between RAN paging and CNpaging messages. Such an alignment may be in terms of RNTIs and/or interms of paging occasions.

For example, a WTRU may monitor a (e.g., single) P-RNTI to receive CNpaging and/or RAN paging messages.

A WTRU may receive a RAN paging message that may be carried in anenhanced legacy paging message. For example, a WTRU may differentiate aRAN paging message from a CN paging message, for example, using an IEsuch as a RAN domain indicator. This may avoid having a WTRU monitor twodifferent P-RNTIs (e.g., one for monitoring RAN paging and/or anotherfor monitoring for a sysinfo modification indication in legacy pagingmessages).

A WTRU may be configured with a RAN paging cycle, for example, as afunction of active services. For example, a RAN paging cycle for URLLCservice may be shorter than MTC service. For example, a RAN paging cyclemay be smaller than a legacy paging cycle, for example, to reduce delayand/or enable faster transition to connected mode.

A WTRU may determine a RAN paging frame and/or RAN paging occasion, forexample, based on WTRU identity associated with a light connection.

There may be a relationship between RAN paging and CN/legacy paging. AWTRU may be configured with a RAN paging cycle that may align with aCN/legacy paging cycle. An alignment may refer, for example, to anarrangement where a CN paging cycle may be an integer multiple of a RANpaging cycle (e.g., a CN paging occasion may overlap with a RAN pagingoccasion). For example, a WTRU may be configured to use the same WTRU ID(e.g., IMSI) for calculation of a RAN paging occasion and/or a CN pagingoccasion. The WTRU may determine the RAN paging occasion using a RANpaging factor. The RAN paging factor may indicate the number of RANpaging occasions between two (e.g., successive) CN paging occasions. Forexample, a value of n for a RAN paging factor may indicate a presence ofn RAN paging occasions between two successive CN paging occasions (forexample, in addition to the RAN paging occasions that coincide with theCN paging occasions). For example, a WTRU may apply a RAN paging cycleto be equal to a CN paging cycle divided by a RAN paging factor. Forexample, a RAN paging factor may be a power of 2. A WTRU may beconfigured with a RAN paging factor in a dedicated signaling. In theabsence of dedicated signaling, a WTRU may determine a RAN paging factorfrom broadcast signaling and/or apply a RAN paging cycle equal to a CNpaging cycle. An eNB may receive and/or store the CN paging cycle and/orthe relevant bits of WTRU ID (e.g., IMSI) from the CN to determineand/or configure a RAN paging factor for a WTRU. FIG. 4 illustrates anexample of overlapping and/or non-overlapping paging occasions.

In FIG. 4 , a WTRU may determine a Radio Access Network (RAN) pagingcycle. The WTRU may determine a Core Network (CN) paging cycle. The WTRUmay determine one or more overlapping occasions between the RAN pagingcycle and the CN paging cycle. The WTRU may monitor, at the one or moreoverlapping occasions, for CN paging and/or RAN paging.

For example, a WTRU may be configured with a (e.g., one) paging cycle(e.g., a RAN paging cycle). A WTRU may monitor for a common pagingmessage. For example, a common paging message may be an enhanced legacypaging message that may include a RAN and/or CN domain indicator. Thismay be beneficial, for example, when there may be a state mismatchbetween a light connected WTRU and a RAN. For example, a WTRU may missRAN paging (e.g., due to an ongoing autonomous mobility event and/or ondemand system information acquisition procedure and/or a RAN paging areaupdate procedure). A WTRU and network may (e.g., as a result of missingRAN paging) have a different understanding of a WTRU state. For example,a network may assume and/or determine that a WTRU went to idle statewhile the WTRU may stay in light connected state. A network may reach aWTRU and/or may synchronize the WTRU state, for example, using a (e.g.,single) paging cycle with a common paging message for CN paging and/orRAN paging.

A WTRU may be identified in a RAN paging message. A WTRU may determinethat a RAN paging message may be addressed to it, for example, based onWTRU identity carried in a RAN paging message. A WTRU may search for aWTRU identity in one or more paging records present in a RAN pagingmessage.

For example, a WTRU may search a RAN paging message for an identityassociated with and/or assigned by a core network (e.g., a GUTI and/orSTMSI).

For example, a WTRU may search a RAN paging message for an identityassociated with the WTRU context stored during light connection.

For example, a WTRU may search a RAN paging message for an identityassociated with a suspended RRC connection.

For example, a WTRU may search a RAN paging message for an identityassociated with light connected state (e.g., an identityreceived/assigned by an anchor NB (e.g., an eNB) that may terminate a CNinterface for the light connected WTRU).

For example, a WTRU may search a RAN paging message for a combination ofRNTI and cell ID (e.g., an RNTI may be associated with a light connectedstate). For example, a cell ID may be associated with an anchor NB thatmay terminate a CN interface for a light connected WTRU.

Terms such as identity, WTRU identity, WTRU identity in the RAN pagingmessage, WTRU identity associated with light connection, etc. may beused interchangeably.

A WTRU in an INACTIVE state may provide assistance for a reachabilityindication. For example, a WTRU may receive a RAN paging message and/ortransmit a RAN paging response (for example, if the paging messagecarries a matching WTRU identity). A RAN paging message may indicatethat WTRU may stay in an INACTIVE state while sending UL response. A RANpaging message may carry an UL grant for a RAN paging response. A WTRUmay be configured to transmit a RAN paging area update message at apreconfigured periodicity. A RAN paging area update message may enable aRAN to provide a WTRU reachability indication to the core network. A RANpaging area update message may enable a RAN to update a RAN-CNinterface.

A WTRU may receive DL data in while staying in an INACTIVE state. Forexample, a WTRU may receive DL data PDU based on a relation to a pagingmessage. The paging message may carry the DCI with DL grant. The pagingmessage may indicate that the WTRU may stay in an INACTIVE state toreceive DL data. The paging message and/or DL data may have predefinedoffset in terms of time unit (e.g., TTI).

A WTRU may transition to connected mode with low latency and/or lowoverhead. A WTRU in light connected state may transition to fullyconnected state, for example, using a Reconnection procedure. AReconnection procedure may be triggered by one or more events. Areconnection procedure (e.g., when data transfer might not be allowedduring a light connected state) may be triggered upon on or more of: anarrival of UL data; an arrival of UL signaling, such as layer 3 and/orNAS (e.g., RAN PA update); and/or upon a reception of a RAN pagingmessage that may indicate DL data arrival. A reconnection procedure(e.g., when a data transfer may be allowed during a light connectedstate) may be triggered upon one or more of: data activity that mightnot match restriction criteria; and/or an arrival of data that might notmatch a stored context.

A WTRU may reconnect with non-ASN signaling. 5G NR may support diversedeployment scenarios, including a flexible split of functionalitybetween a central unit and a remote unit. Light connectivity may besupported in a distributed control plane and/or user plane architecture.A WTRU may establish context with a central control function. A lightconnected WTRU may autonomously move between edge control functions,e.g., while retaining layer 3 context and/or parts of layer 2 context. AWTRU may perform a reconnection procedure with an edge control function,for example, using non-ASN signaling (e.g., for layer 2 signaling). Atarget edge control function may (e.g., upon receiving a WTRU requestfor reconnection) interact with a source edge control function and/orcentral control function to retrieve WTRU context. A WTRU securitycontext may be anchored at a central control function. A WTRU might notderive new keys upon a change in edge control function. For example, aWTRU may be configured with list of cells where the WTRU may apply acommon security context. For example, the cells for which the WTRU mayapply a common security context may be indicated in broadcast signaling(e.g., system information). In such case, for example, the WTRU mayapply a common security context in some or all cells which broadcast thesame security context ID, while the WTRU may initiate a security contextrefresh in the case where the WTRU moves to a cell with a differentsecurity context ID. For example, a use for a security context updatemay be determined by the cell ID itself, where some predeterminedgrouping of cell IDs may allow transmission with a common securitycontext. A reconnection procedure may refer to a layer 3 connectionprocedure and/or a layer 2 reconnection procedure.

A WTRU may provide scheduling assistance to a network during areconnection procedure. For example, a WTRU may include one or more ofthe following: a buffer status report (e.g., with a reconnectionrequest); latency requirements/status (e.g., with a reconnectionrequest); layer 2 status (e.g., RLC/PDCP status); a WTRU identity (e.g.,associated with light connection); a context identifier (e.g., may beassociated with the WTRU and/or a context for a WTRU); a reason forreconnection (e.g., mobile originated (mo)-signaling (such as RAN PAupdate and/or NAS signaling), mo-data and/or response to RAN paging);and/or an indication of the DRBs/flows to be resumed for data transfer.

A re-connection procedure may be optimized/parameterized/configured toachieve one or more of low latency and/or low overhead. Low latency maybe provided, for example, by reducing the time taken from the arrival ofdata to the actual transmission of data for a WTRU in light connectedstate). Low overhead may be provided, for example, by reducing theamount of signaling overhead to transmit data PDU. For example, theremay be a reduction in the number of message exchanges over the airinterface to setup the connection.

A reconnection request may be provided with on-demand systeminformation. A WTRU may (e.g., upon entering a new cell) acquireon-demand system information, e.g., before triggering a reconnectionprocedure. A WTRU may (e.g., to reduce latency due to sequentialprocedures) combine an on-demand system information request with areconnection procedure. A network may provide (e.g., the most essential)system information for the type of service requested, for example, giventhat a reconnection request may include information about UL dataarrival. For example, a WTRU may set a system information field as“true” in a reconnection request message.

A reconnection request may be provided with a RAN PA procedure. A WTRUmay (e.g., upon entering a new RAN Paging area) perform a RAN PA update,e.g., before triggering a reconnection procedure. A WTRU may combine aRAN PA update procedure with a reconnection procedure, for example, toreduce latency due to sequential procedures. For example, a WTRU may setRAN PA update field to “tru” in a reconnection request message.

A fast reconnection procedure may be provided. A WTRU may (e.g., toreduce latency and/or overhead associated with a reconnection procedure)be configured to use dedicated resources in light connected state toperform a faster reconnection procedure.

A WTRU may transition to connected mode using one or more dedicatedresources, for example, based on the existence of one or more factors,such as one or more of: where/when there may be an UL data arrivalduring a light connected state; when/where a WTRU may be configured withone or more dedicated resources for light connectivity operation and/orthe validity of those resources has not expired; and/or a WTRU maydetermine its location to be within a validity region.

One or more radio resources that may be specific to light connectivityoperation may be configured at the time a WTRU enters a light connectedstate (e.g., using a control message from the network), perhaps forexample during a response to a RAN paging area update procedure and/orin the RAN Paging message. Radio resources may include, for example, arandom access preamble, a random access time/frequency resource and/or anon-orthogonal resource. Radio resources may be dedicated to a WTRU, toa group of WTRUs, and/or may be common to (e.g., one or more, or all)WTRUs in a light connected state.

A validity timer may associated with a dedicated and/or common resource.A validity timer may be an absolute value and/or may be a function ofWTRU activity. For example, a validity timer may be extended forexample, when the WTRU may be highly active. A validity timer may be afunction of a type of service. A URLLC service may be associated with alonger validity timer than an eMBB service.

A validity region may be associated with a dedicated resourceconfiguration. For example, a validity region may be a cell from which aWTRU may receive a light connectivity configuration. For example, avalidity region may correspond to a logical RAN paging area and/or asub-area thereof. A validity region may be a function of a type ofservice and/or a WTRU mobility state.

A WTRU may release (e.g., stop transmission and/or reception on) adedicated and/or common resource, for example, when a validity timerexpires and/or when a WTRU moves out of a validity region.

A validity timer and/or validity region associated with a dedicatedand/or common resource configuration may be different from a validitytimer and/or validity region associated with a light connectivity state.For example, a WTRU may be configured with a validity timer for adedicated and/or common resource configuration to be shorter or equal toa validity timer for a light connectivity state. A WTRU may beconfigured with a validity region for a dedicated and/or common resourceconfiguration to be a subset of a validity region for a lightconnectivity state. A configuration may allow a WTRU to release adedicated and/or common resource at a different time and/or place thanan exit from a light connected state.

A reconnection request may be provided with a data PDU. A WTRU maydetermine whether a scheduling grant for sending a reconnection requestmay be greater than a predefined threshold. A scheduling grant may begreater than a predefined threshold, a WTRU may multiplex data PDU(s)and/or part of a data PDU, e.g., along with a reconnection requestmessage.

For example, a WTRU (e.g., when it may have an excess grant) may includeadditional information along with a reconnection request, such as one ormore of the following: data PDU and/or part of data PDU whose latencybudget may be lower than a predefined threshold; piggybacked RRC/NASmessage (e.g., on-demand SIB request, RAN PA update, and/or TrackingArea update, etc.); scheduling assistance information; and/or one ormore (e.g., all) other data PDU and/or part of data PDU. For example, aWTRU may include a Data PDU (e.g., only) when an excess grant may allowfor more than a predefined threshold (e.g., x bytes) of a data PDU to betransmitted.

A WTRU may be configured to perform a reconnection procedure withmobility information. For example, a WTRU may receive a RRC ReconnectionConfiguration message (and/or similar) with mobility control informationas a response to a reconnection message. The RRC ReconnectionConfiguration message (and/or similar) with mobility control informationmay be used to update one or more configuration aspects (e.g., PHY/MACconfiguration aspects) of the WTRU. The RRC Reconnection Configurationmessage (and/or similar) with mobility control information may be usedto update the WTRU’s security context. For example, the WTRU may performderivation of new keys when it receives such message using theapplicable key derivation mechanism and/or the security-relatedinformation in the message.

A WTRU may be configured to perform a reconnection procedure withoutmobility information. For example, a WTRU may receive a RRC ReconnectionConfiguration message (and/or similar) without mobility controlinformation as a response to a reconnection message. The RRCReconnection Configuration message (and/or similar) without mobilitycontrol information may be used to update one or more configurationaspects (e.g., PHY/MAC configuration aspects) of the WTRU, if suchinformation elements are present in the message. The RRC ReconnectionConfiguration message (and/or similar) without mobility controlinformation may be used, for example, when a WTRU is to continuesecurity using the stored security context (e.g., the a WTRU might notperform derivation of new keys). Continuing with previous security keysmay simplify a reconnection when the WTRU has not changed cell since thelast time it was in CONNECTED mode.

Reconnection failure handling may be provided. A WTRU triggeredre-connection procedure may fail, for example, when WTRU context mightnot be found in a network.

A WTRU and network (e.g., in case of a reconnection failure) maycoordinate to establish an RRC connection, perhaps for example withouthaving to start from random access again.

A WTRU may determine whether additional grants may be received with areconnection failure message and/or whether valid grants may be present.A WTRU may use those grants to establish and/or re-establish an RRCconnection. A WTRU may use a timing advance received from a randomaccess procedure during a reconnection procedure for a RRC connection(re-) establishment procedure.

A WTRU context may be recovered based on a pre-existing RAN-Coreinterface. A WTRU may assist a RAN to recover an RRC context from apre-existing RAN-Core interface and/or WTRU context at the core. A WTRUmay trigger a core network to establish a WTRU context in RAN. A WTRU(e.g., upon reconfiguration failure) may perform NAS triggered RRCconnection recovery (NRC), for example, rather than full establishment.A WTRU may use resources obtained as a result of a reconnectionprocedure to perform an NRC procedure. For example, a WTRU may transmitan NRC message (e.g., a Tracking area update) and/or an NAS message totrigger an NRC procedure. For example, an NRC procedure may bepiggybacked with an RRC connection, reconnection and/or reestablishmentprocedure. A WTRU may include additional information in an NRC message.Additional information may be related to a core control function entity,WTRU identity allocated by the core network and/or a context/cookie withaspects related to preexisting core control plane context, etc. A RANnode (e.g., upon failure to recover a WTRU context at RAN level) mayforward an NRC message to a core network. A core network may detect anNRC procedure, for example, when it receives a tracking area updateand/or NRC message for a WTRU in ECM_CONNECTED state. NRC may be treatedas an S1 handover, e.g., from a network point of view.

A light connection release procedure may be provided. A WTRU may exit alight connectivity state and/or may move to idle state, for example,when one or more of the following conditions may be satisfied/true.

For example, a condition/factor may be elapsed time, e.g., when datatransfer might not be allowed and/or a WTRU may stay in light connectedstate without transition to connected state for a predefined period oftime.

For example, a condition/factor may be inactivity, e.g., when datatransfer may be allowed in light connected state and/or the volume ofdata transfer over a predefined time window may be below a threshold.

For example, a condition may be a WTRU mobility state. WTRU powerconsumption in light connected state may depend on a frequency of celland/or paging area updates, which may be a function of WTRU speed. AWTRU may monitor the number of mobility events in a predefined timeinterval. A WTRU may exit light connected state, for example, when anumber of mobility events may be higher than a predefined threshold. AWTRU may transition from light connected state to idle state, forexample, when a number of cell changes and/or a number of RAN PA updatesin a predefined time interval may be greater than threshold.

For example, a condition may be a WTRU location. Light connectivitystate for a WTRU may be associated with a logical area. For example, aWTRU may exit light connected state upon leaving current cell, RAN PAand/or Tracking area. For example, WTRU location may be abstracted by ameasurement of system signature/reference signal.

For example, a condition may be reselection to a new layer/RAT. Forexample, a light connected WTRU in NR layer may exit light connectedstate upon reselecting a RAT that might not support light connectivity(e.g., 3G, 2G cell) and/or might not support NR light connectivityinterworking (e.g., LTE).

For example, a condition may be a received command from a network. Forexample, a command may be received in a RAN Paging message and/or RAN PAupdate response message.

For example, a condition may be arrival of UL/DL data for aservice/slice/QoS that might not be supported by the stored lightconnectivity configuration.

For example, a condition may be a RAN paging failure. A WTRU in lightconnected state may monitor for a possible RAN paging message, e.g., atevery RAN PA DRX cycle. A WTRU may exit light connected state, forexample, when the WTRU is unable to monitor RAN paging (e.g., due toinability to reliably decode a control channel) for N or more occasionsover a time interval. For example, a WTRU may declare a RAN pagingfailure, for example, when a WTRU did not monitor the RAN paging channelfor N consecutive paging opportunities.

For example, a condition may be a system information update, e.g., aperiodically broadcast update and/or an update initiated by a networkthrough a paging message.

Core network load balancing may be provided for light connected WTRUs. AWTRU in a light connected state may be (e.g., still) considered as ECMCONNECTED, e.g., from a core network control function (e.g., MME) pointof view. This mismatch in WTRU state may cause an issue for an MMEtriggered procedure that may assume a certain WTRU state. For example,an MME may (e.g., for load balancing purposes ) trigger S1 CONNECTIONrelease with release cause ‘load balancing TAU required.’ An eNB may(e.g., for a WTRU in RRC CONNECTED state) transmit RRC CONNECTIONrelease with cause ‘loadbalancingTAU required.’ A WTRU may move to RRCIDLE and/or perform a TAU procedure. An eNB might not reach a WTRU thatmay be in light connected state with a dedicated RRC message, which maybe addressed by other techniques.

A WTRU may release a light connectivity configuration, transition toidle state and/or perform tracking area update, for example, when itreceives a RAN paging message with a TAU required/useful indication.

A core network may internally handle load balancing. A network may(e.g., to update a core-RAN interface) utilize a reachability functionto trigger a WTRU to update its position. For example, a WTRU maytrigger a RAN PA update procedure, for example, upon receiving a RANPaging message with target MME information. A RAN node receiving a RANPA update may interact with a target MME to setup a core-RAN interface.

A WTRU may take one or more actions upon leaving light connectivity,such as one or more of the following actions: delete storedconfiguration applicable to light connectivity; clear an outstanding RANPA update, and/or RAN Paging response, etc.; stop a running validitytimer associated with a light connectivity; stop a running validitytimer associated with common and/or dedicated resources configured withlight connectivity; and/or enter an IDLE state and/or a CONNECTED state,e.g., based on the scenario (e.g., a trigger that caused an exit fromlight connectivity).

A WTRU (e.g., upon transition to IDLE state) may take one or more of thefollowing actions: reset L2 state and/or flush HARQ and/or ARQ buffers(e.g., when data transfer was allowed in a light connected state);release (e.g., stop transmission and/or reception on) any dedicatedresources; trigger on-demand system information (e.g., when WTRU wasbased on stored configuration); and/or trigger a tracking area update(e.g., to reset the core-RAN interface and/or synchronize NAS state).

A WTRU (e.g., upon transition to a CONNECTED state) may take one or moreof the following actions: retain layer 2 state (e.g., HARQ/ARQ buffers,and/or state variables, etc.); and/or overwrite a layer 2 configurationwith the received dedicated radio resource configuration associated withthe CONNECTED state.

A WTRU (e.g., exiting light connected state based on WTRU rules and/orentering IDLE state) may inform the network of the change in state. AWTRU may send a new and/or dedicated message and/or a modified RAN PAupdate message. For example, a WTRU indication may be required/useful,for example, when dedicated resources may be configured for the WTRUand/or a network may release radio resources and/or a core-RAN interfaceassociated with the WTRU. For example, a WTRU may leave a lightconnected state without a network indication and/or a network maydetermine a state transition based on an absence of a RAN pagingresponse. A network may (e.g., then) try to reach a WTRU, e.g., using CNpaging based on an IDLE mode DRX cycle.

A WTRU may enter dormant light connectivity, for example, when it goesout of coverage and/or enters a cell that might not support lightconnectivity. A WTRU (e.g., in dormant light connectivity) may store alight connectivity configuration and/or may behave like an idle modeWTRU.

A WTRU (e.g., in dormant light connectivity) may reselect to a cellsupporting light connectivity. A validity timer may (e.g., still) berunning. The WTRU may re-enter light connected state, for example, whenthe cell belongs to the same RAN PA corresponding to the stored lightconnectivity configuration. The WTRU may perform RAN PA update procedureand/or may re-enter light connected state, for example, when indicatedin the RAN PA update response message that the cell belongs to adifferent RAN PA. The WTRU (e.g., when the validity timer expires) mayperform actions upon leaving a light connected state and/or maytransition to idle state, e.g., as previously discussed.

A WTRU may store a light connectivity configuration, e.g., upontransition to connected state. A WTRU may activate a storedconfiguration upon leaving connected state and/or during a failure eventin a connected state.

Measurement configuration and/or reporting may be provided. Targetedmeasurement resources may be provided. WTRU measurements on a defaultset of subcarriers over a minimum bandwidth might not be accurate indeployments, for example, where the operating bandwidth of neighborcells and/or serving cells might not be same. RSRP/RSRQ measurementsover central subcarriers may be optimistic and/or might not representthe true interference situation. Measurements may be performed overwider bandwidth, although WTRU power consumption may increase due tomeasurements over large system bandwidth (e.g., 80Mhz for NR). A WTRUmay account for difference in numerology between different parts of aserving cell BW and/or difference in numerology between serving andneighbor cells.

A WTRU may perform measurements over a targeted set of resources thatmay be dynamically configured per cell, for example, as compared toperforming measurements over central subcarriers over minimum BW.Measurement resources may be chosen as a function of serving and/orneighbor load and/or may take into account WTRU capability to performmeasurements that may be used to achieve a desired level of accuracy.

Targeted measurement resources may be a function of WTRU state. Forexample, WTRUs in light connected state may perform measurements overresources that correspond to RAN paging. RAN paging resources mayinclude control channel resources that may schedule RAN paging and/ordata channel resources that may carry a RAN paging message. WTRUmeasurements in light connectivity may (e.g., thus) be indicative of thequality of RAN paging resources. A WTRU may perform autonomous mobility,for example, such that the probability of receiving RAN paging may beabove a predefined threshold.

A WTRU may (e.g., in addition to measurements related to radio linkquality for RRM and/or mobility) measure aspects related to datatransmission during light connectivity. For example, a WTRU may keeptrack of its data transmission activity during light connectivity and/ormay report to the network based on pre-defined triggers, e.g., datavolume exceeding a threshold, data volume below a threshold, etc. Forexample, a WTRU may monitor mobility events during light connectivity(e.g., a number of paging area updates over a time interval, etc.). AWTRU may report measurements, e.g., along with a paging area updatemessage.

Power consumption may be reduced during light connectivity. WTRUmeasurement procedures in light connectivity may be optimized to reducepower consumption while maintaining reasonable measurement accuracy. Forexample, reference signals that may be used by a WTRU may perform RRMand/or mobility measurements, e.g., as a function of WTRU state. Forexample, a WTRU (e.g., in a connected mode) may perform measurements oncell specific reference signals (e.g., CRS and/or the like) and/or WTRUspecific reference signals. For example, a WTRU (e.g., in a lightconnected mode) may perform measurements on reference signals specificto one or more groups of TRPs (e.g., a system signature and/or thelike). For example, a system signature may be common to a RAN pagingarea.

A WTRU may limit the number of neighbor cells to measure and/or track ina light connected state. For example, a WTRU may (e.g., as a function ofserving cell threshold) have different levels of measurements, forexample, to restrict neighbor cells to (e.g., only) neighbors in thecurrent RAN PA, restrict to best neighbor per RAN PA, etc. A WTRU maylimit the number of neighbor cells to measure as a function of WTRUmobility state. A WTRU may avoid or minimize neighbor measurements, forexample, when a WTRU may be stationary and/or a serving cell may beabove an acceptable threshold. A WTRU may perform a neighbor measurementevaluation at a reduced rate (e.g., at a multiple of RAN paging cycleduration), for example, instead of every RAN paging cycle.

A WTRU may determine to perform inter-RAN PA autonomous mobility, forexample, based on measurement results. For example, a WTRU may (e.g.,first) shortlist the number of neighbor cells above a predefinedthreshold. A WTRU (e.g., when the number of shortlisted cells belongingto a non-serving RAN PA may be higher than the number of cells belongingto a serving RAN PA) may select the best cell in a non-serving RAN PAand/or may perform inter-RAN PA mobility. For example, inter-RAN PAmobility may be based on measurements on RAN PA specific systemsignature. For example, a WTRU may perform inter-RAN PA mobility, forexample, when measurements of the system signature of a non-serving RANPA may be offset above the serving RAN PA. A WTRU may add additionalbias to neighbor cells belonging to a serving RAN PA, for example, toavoid additional overhead caused by a RAN PA update procedure. A WTRUmay select a best neighbor cell, for example, based on measurementresults. A WTRU may perform mobility action with or without indication(e.g., RAN PA update) to a network, for example, based on a selectedcell’s RAN PA (e.g., serving and/or non-serving).

Mobility may be provided during light connectivity. A WTRU may triggerautonomous mobility based on one or more of: an availability of a (e.g.,better) cell from a link quality perspective (e.g., based on measurementresults); an availability of a (e.g., better) cell from a serviceperspective (e.g., support of services associated with the lightconnectivity configuration); an availability of a better cell from aresource availability perspective (e.g., cells may broadcast averageload of resources such as random access resources, number of activeWTRUs in the cell, and/or average resource utilization in the cell,etc.) so that a WTRU may perform autonomous mobility towards the cellthat may be lightly loaded; and/or availability of a better cell from acapability perspective (e.g., a WTRU may select cells that support widerbandwidth and/or shorter TTI, etc.).

A WTRU may perform an accessibility check on a target cell, for example,as a part of an autonomous mobility procedure. An accessibility checkmay include determination of barred status of the cell, verification ofaccess class, etc. Access class may be a function of WTRU state. Forexample, a special access class may be defined that may determinewhether a light connected WTRU may access the cell. A light connectivityaccess class may be interpreted by a WTRU in one or more ways aloneand/or in any combination. A WTRU may determine whether it can considera cell for autonomous mobility based on the light connectivity accessclass associated with that cell. A WTRU may determine whether it canperform WTRU triggered reconnection to a cell based on the lightconnectivity access class associated that cell. For example, a WTRU may(e.g., when a reconnection may be barred) perform RRC connection(re)establishment on the cell and/or wait for DL RAN paging. A WTRU maydetermine whether it can perform reconnection for signaling (e.g., only)and/or for signaling and/or data in a cell based on the lightconnectivity access class associated with that cell. For example,reconnection in a cell may be allowed (e.g., only) for signaling and/ornot for data. A WTRU may determine whether it can perform reconnectionfor a specific service, for example, based on the light connectivityaccess class associated with that service. For example, reconnection ina cell may be allowed for URLLC service and/or not eMBB service.

A network may (e.g., perhaps instead of an explicit access class)perform admission control for light connected WTRUs, e.g., based on areceived reconnection request. For example, a network may reject areconnection. A WTRU may (e.g., then) move to idle mode, performreselection and/or establish RRC connection from scratch. A WTRU may useredirection information in the reconnection reject, e.g., to resume theconnection in a different cell.

Prioritized autonomous mobility may be provided. A WTRU (e.g., whenperforming autonomous mobility) may (e.g., perhaps in addition toquality of measurement results) prioritize cells using one or morecriteria such as: prioritize cells from a current RAN PA and/or a (e.g.,same) RAN control function, which may reduce performing a RAN PA updateand/or RAN control plane context relocation; prioritize cells from a(e.g., same) tracking area and/or core control function, which mayreduce performing a tracking area update and/or core control planerelocation; prioritize cells that may support one or more services thatmay be suspended (e.g., due to light connectivity); prioritize cellsthat may support light connectivity; and/or prioritize cells with a sametype of radio interface (e.g., NR and/or LTE), same frequency, and/orsame numerology, etc.

A WTRU may perform prioritization, for example, by applying a biasfactor to the measurement quality of the cells.

A WTRU may (e.g., upon selecting a target cell for autonomous mobility)determine whether a target cell belongs to the same RAN PA as the sourcecell or a different RAN paging area. WTRU actions may depend on thetarget cell’s RAN paging area. For example, a target cell may belong tothe same RAN PA as the source cell. A WTRU may start to perform a lightconnectivity operation (e.g., monitor the target cell control channelfor RAN paging message and/or trigger reconnection based on UL dataarrival, etc.). A WTRU may perform a RAN paging area update procedure,for example, when a target cell may belong to a different RAN Pagingarea. A WTRU may perform an on-demand system information procedure toacquire relevant system information for a target cell, for example, whenthe WTRU does not have valid stored system information relevant forlight connectivity operation in the target cell. A WTRU may monitor apaging channel on a source cell, for example, until completion of a RANpaging update procedure. A WTRU (e.g., upon successful completion of aRAN paging update procedure) may start to monitor a control channel on atarget cell. A WTRU may wait for completion of a RAN paging updateprocedure (e.g., when there may be a UL data arrival during theprocedure) before triggering a reconnection and/or usingcommon/dedicated resources in a target cell that may be available duringlight connected state.

A WTRU may determine what part of stored configuration remains validduring an autonomous mobility procedure. A WTRU may make a determinationwithout an explicit signaling exchange with the network. For example, aWTRU may remember/store a linkage between a configuration and a controlfunction that may have triggered a configuration. A WTRU (e.g., upon achange in the entity associated with a control function) may consider acorresponding configuration to be invalid. For example, a WTRU mayconsider a configuration received from an edge control function to beinvalid upon autonomous mobility to a different edge control function.For example, a WTRU may remember/store an association between a receivedconfiguration and a transport mechanism used for a configuration. Forexample, a WTRU may associate a configuration received via layer2/layerlsignaling with a transmission point and/or may associate a configurationreceived via layer3 signaling with a RAN paging area. A WTRU (e.g., uponautonomous mobility to a different transmission point) mayinvalidate/release a configuration received via layer2/layer1 signalingwhile maintaining a configuration received via layer3 signaling.Configuration in this context may include configuration applicable to a(e.g., any) protocol layer. Longevity of a configuration may bedetermined, for example, by a transport mechanism used totransmit/receive the configuration.

A WTRU may determine what portions of a WTRU protocol state may persistduring an autonomous mobility procedure using one or more of proceduresalone and/or in any combination.

A WTRU may determine what portions of a WTRU protocol state to persistbased on a relation with a reference signal. A relation with a referencesignal transmitted by a TRP may indicate how much WTRU context may beshared between TRPs. For example, a reference signal may be a cellspecific reference signal and/or a logical identity associated with areference signal sequence (e.g., cell ID and/or similar).

A WTRU may determine what portions of a WTRU protocol state to persistbased on broadcast information. For example, an access table and/orsystem information broadcast may indicate a relationship with a neighborcell (e.g., whether HARQ buffer may be shared, an ARQ may be sharedand/or a security may be shared).

A WTRU may determine what portions of a WTRU protocol state to persistbased on location. A WTRU may determine layer 2 handling, for example,based on the location of a transmission point and/or cell. For example,a WTRU may retain a layer 2 context upon autonomous mobility to a cellin the same RAN paging area. A WTRU may reset a layer 2 context uponautonomous mobility to a cell to a different RAN paging area.

A WTRU may assume that a portion or all of a stored configuration and/orWTRU state may survive irrespective of autonomous mobility. A WTRU mayhold on to a context until it receives a response to reconnectionrequest. A reconnection response may indicate what part of aconfiguration and/or WTRU context to retain. A WTRU may delete/reset theparts of a WTRU context that are not indicated in a reconnectionresponse. This approach may hide the network deployment/architectureand/or backhaul/fronthaul implementation, e.g., from the WTRU point ofview.

A mobility paradigm for a WTRU may be a function of WTRU state and/orallowance of data transfer in that state. For example, a WTRU mayperform autonomous mobility without notifying the network, for example,when data transfer might not be allowed in a light connected state. AWTRU may transition to a connected state to perform data transfer and/orin connected state WTRU mobility may be controlled by the network. Forexample, a WTRU may perform autonomous mobility and/or may indicate tothe network (e.g., after a mobility event) when data transfer may beallowed in light connected state. A WTRU may transmit an indication to atarget cell while being connected to the source cell. An indication mayinclude additional information for a target cell to acquire a WTRUcontext from a source cell.

WTRU autonomous mobility and/or data transfer in light connected statemay result in data PDUs buffered at different network nodes.

A WTRU may delay autonomous mobility, for example, until data transferis completed while in a light connected state. For example, a smalloffset factor may be added to serving cell quality, for example, whendata transmission is active during light connected state.

A WTRU may suspend data transmission, for example, when autonomousmobility may (e.g., does) result in a cell change. A WTRU may resume adata transfer in a target cell, for example, after completion ofautonomous mobility. Completion of autonomous mobility may includesystem information acquisition in the target cell, a RAN paging areaupdate and/or availability of a (e.g., valid) UL timing advance.

A WTRU may indicate the identity of a source cell and/or availability ofdata PDUs at the source cell, for example, upon resumption of datatransfer in a target cell.

A WTRU may perform autonomous mobility (e.g., only) within an allowedarea. For example, a WTRU may perform light connected mobility withinone or more (e.g., all) RAN paging areas of a tracking area associatedwith a central control function. A WTRU (e.g., upon moving to a celloutside of an allowed area) may exit a light connected state, performactions when leaving light connected state, perform tracking area updatewhen applicable and/or may (e.g., subsequently) move to idle state. AWTRU may restrict its autonomous mobility to transmission points withthe same type of radio interface (e.g., NR and/or LTE), same frequency,same numerology, etc.

For example, the WTRU may initiate the RRC Connection Re-establishmentprocedure upon determining that the WTRU has moved outside a RAN PagingArea of its configuration. If the WTRU is configured with multiple RANpaging areas, when the WTRU determines that it is outside any of the RANPaging Areas of its configuration, the WTRU may initiate an RRCConnection re-establishment procedure. For example, the WTRU maydetermine that the WTRU has moved outside a RAN Paging Area if the WTRUdoes not detect a suitable cell associated with one of its configuredRAN paging area(s). Performing RRC Connection Re-establishment when theWTRU moves outside its RAN paging area may help avoid loss ofsynchronization between the WTRU and the network (e.g., as a consequenceof the RAN no longer knowing where to reach the WTRU within anapplicable RAN Paging Area and/or as a consequence of the MME notmanaging the concerned WTRU as an IDLE mode WTRU (e.g., the MME may beunaware of the WTRU no longer being managed by the RAN at least untilthe RAN can make such determination, e.g., following timer expiration asdescribed above and/or similar).

LTE and/or 5G NR may be (e.g., tightly) integrated for lightconnectivity. A WTRU may be light connected in one RAT and/orlight/fully connected in another RAT. Interworking between RATs may bedefined according to RRC states, e.g., inter-RAT reselection betweenEUTRAN and non-EUTRA RATs for IDLE WTRUs and/or inter-RAT handoverbetween EUTRAN and non-EUTRA RAT for CONNECTED WTRUs. LTE and/or NR mayhave tighter modes of interworking, e.g., to allow for a phaseddeployment of NR. WTRUs in light connected state may perform mobilitysimilar to idle mode mobility between LTE and NR. A reselection basedmechanism may result in service interruption and/or cause a WTRU tosetup a context from scratch.

A WTRU context available in one RAT may be reused, for example, when theWTRU moves to another RAT. Inter-RAT light connected mobility (e.g.,from a core network point of view) may seem like an inter-RAT handover.Different levels of reuse may be defined. For example, a context may beshared, transferred and/or converted.

A WTRU in a light connected state may perform inter-RAT mobility usingone or more procedures alone and/or in any combination.

A WTRU in a light connected state may perform inter-RAT mobility, forexample, using Inter-RAT Re-connection. A WTRU may move from one RAT(NR/LTE) to another RAT (LTE/NR) while staying in light connected state.A WTRU (e.g., upon reselecting to a new RAT) may perform a reconnectionprocedure that may be defined for the new RAT. For example, an RRCconnection resume may be used for reconnection in LTE RAT. A WTRU mayinclude source RAT information (e.g., cell ID, RAT type, WTRU contextID, etc.) in an inter-RAT Re-connection message. A target RAT may obtaina WTRU context from a source RAT, add/delete/modify the lightconnectivity configuration (e.g., as per the needs/capabilities of thetarget RAT) and/or may transmit a re-connection response.

A WTRU in a light connected state may perform inter-RAT mobility, forexample, using Inter-RAT RAN PA update. A WTRU (e.g., upon entering anew RAT) may perform a RAN PA update, for example, when RAN Paging areasbetween LTE and NR may be independent. A WTRU may include source RATinformation (e.g., similar to a re-connection). A RAN PA response maycontain paging configuration, services to be resumed in the target RAT,etc.

A WTRU in a light connected state may perform inter-RAT mobility, forexample, using Inter-RAT Re-establishment. A light connected WTRU in NRRAT may enter LTE RAT, may perform an RRC Re-establishment and/or (e.g.,upon successful reestablishment) transition to a connected state. A WTRUmay do this, for example, when light connection might not be supportedin LTE RAT. A WTRU may include source RAT information. A WTRU may, forexample, set the contents of an RRCConnectionReestablishmentRequestmessage as follows: set C-RNTI in ReestabWTRU-Identity as a predefinedvalue (e.g., from FFF4-FFF9), for example, to indicate that a WTRU maybe coming from NR and/or that a context ID may be used to fetch the WTRUcontext; set physCellId to the identity of the last NR cell; and/or setreestablishmentCause as lightmobilityfromNR.

A WTRU in a light connected state may perform inter-RAT mobility, forexample, using an enhanced RRC connection request. A light connectedWTRU in an NR RAT may enter LTE RAT, transition to idle mode and/or mayperform an enhanced RRC connection request. A WTRU may do this, forexample, when light connection might not be supported in LTE RAT. A WTRUmay include source RAT information and/or establishmentCause aslightmobilityfromNR.

A WTRU in a light connected state may perform inter-RAT mobility, forexample, using WTRU assisted handover. A WTRU in light connected statein a source RAT (e.g., upon discovering a better and/or high prioritytarget RAT) may transmit a measurement report that may contain thetarget RAT information. The source RAT may trigger handover to thetarget RAT, which may be seen as inter-RAT handover (e.g., from thetarget RAT and/or WTRU point of view).

A WTRU in an RRC state associated to a first RAT (e.g., in a sourcecell) may receive a reconfiguration that may include specificparameters. The WTRU may determine from the parameters what RRC state(e.g., a target RRC state) to use in the second RAT (e.g., in a targetcell). For example, the WTRU may perform autonomous mobility between twodifferent RATs while in an INACTIVE state and/or a light connectedstate.

The WTRU may determine that the received reconfiguration enables aspecific state such as RRC INACTIVE (and/or light connected state) (forexample, if the proper configuration is included (e.g., the presence ofWTRU context ID), and/or based on the RRC message received, and/or basedon the procedure followed for such reconfiguration. For example, a WTRUin a connected state associated with a source RAT (e.g., LTE/NR) mayreceive a mobility-command in a RRC reconfiguration message and/or a RRCconnection release message with a redirection information.

A WTRU in an INACTIVE state in NR, and/or light-connected state in LTE,may receive a mobility-command in a RAN paging message and/or in aresponse to resume request from the WTRU, e.g., as a result of UL dataarrival and/or response to RAN paging.

The mobility-command may include a target RAT type (e.g., NR/LTE) and/ora transparent container indicating radio resource configurationapplicable for the target RAT (e.g., NR/LTE), including the radio bearerconfiguration and/or target cell information. The WTRU may determine oneor more of the following aspects from the mobility-command: a target RRCstate, an area configuration for the target RAT, and/or a type of corenetwork. A target RRC state may be a RRC state applicable for the targetRAT after the mobility event, e.g., may indicate CONNECTED or IDLE modeor INACTIVE/Light connected as applicable for the target RAT. The RRCstate in target state may be implicit from the message carrying themobility-command, e.g., the WTRU may assume that the RRC state in thetarget RAT is an IDLE state (for example, if no explicit stateinformation is present in RRC connection release message). An areaconfiguration for the target RAT may be provided. For example, if thecell in the target RAT belongs to the same RAN area as the source celland/or a different RAN area, logical identifier and/or a list of cellsbelonging to a RAN area in the target RAT etc. A WTRU may be configuredonly with a target RAT frequency without a target cell information(e.g., when target RRC state is INACTVE, light connected and/or IDLE). AWTRU may select a suitable cell in the configured RAN paging area of thetarget RAT. Type of core network (e.g., EPC and/or NGC) may be supportedin the target RAT. A WTRU may assume that a source RAT and a target RATbelong to a common core network (for example, if source and target cellsbelong to same RAN area). If the target RAT is NR, then a WTRU mayreceive configuration aspects related to numerology, control channels,beamforming configuration, etc.

Upon receiving the mobility-command, the WTRU may take one or more ofthe following actions: reset MAC (including, for example, SCG MAC ifestablished) associated with source RAT; re-establish RLC (including,for example, SCG RLC if established) for one or more, or all, SRBsand/or DRBs; perhaps if the target RRC state is INACTIVE and/or Lightconnected: store CRNTI, PCI and/or cell-identity of source cell, WTRUcontext identity, source RAT type, and/or identity of control planeentity in the CN, etc.; and/or perhaps if the target RRC state is IDLE:release one or more, or all, radio resources associated with a sourceRAT, including release of the RLC entity, the MAC configuration and/orthe associated PDCP entity for one or more, or all, established RBs;and/or indicate the release of the RRC connection to upper layersperhaps together with the release cause.

A WTRU may apply the radio resource configuration received in themobility-command for the target RAT. For configuration aspects notpresent in the mobility-command, the WTRU may apply a defaultconfiguration pre-defined for the target RAT. The WTRU may perform DLsynchronization towards the target cell (e.g., if not performedalready). The WTRU may determine the criteria for success or failure ofthe mobility procedure as a function of RRC state configured for thetarget RAT. For example, if the target RRC state is INACTIVE stateand/or Light connected: the WTRU may acquire system information from theconfigured target cell (and/or from a suitable cell selected in thetarget RAT), e.g., if not already provided in mobility-command. The WTRUmay determine that the mobility procedure is successful if the WTRU isable to acquire system information required/useful for operation in thetarget RAT. The WTRU may instantiate SRB(s) and/or one or more DRB(s)according to the bearer configuration in the received mobility-command.The WTRU may activate one or more SRB(s)/DRB(s) if data transfer issupported by the target RAT in the target RRC state, otherwise the WTRUmay suspend the configured radio bearers. If the target RRC state isCONNECTED state: the WTRU may determine that the mobility procedure issuccessful if a random access procedure is completed in the target RAT.If the target RRC state is IDLE state: the WTRU may determine that themobility procedure is successful if the WTRU is able to camp on theconfigured cell and/or a suitable cell in the target RAT.

Upon a successful mobility procedure towards the target RAT, a WTRU mayrelease some or all radio resources associated with a source RAT,including release of the RLC entity, the MAC configuration, and/or theassociated PDCP entity for some or all established RBs. The WTRU mayperform a confirmation procedure that is a function of WTRU state in thetarget RAT. If the target RRC state is INACTIVE state and/or Lightconnected: the WTRU may perform RAN area update procedure defined forthe target RAT (e.g., if the target cell is in a different RAN area).The WTRU may include the type of source RAT, cell ID of the source cell,WTRU context identity received in the source RAT. The WTRU may includethe identity of CN control plane entity. If the target cell is in thesame RAN area as the source cell, the WTRU might not perform RAN areaupdate procedure. If UL data is pending for transmission, the WTRU mayuse one or more access methods defined in the target RAT to transmit ULdata (e.g., if UL data transmission is allowed in the target RAT whilein INACTIVE and/or Light connected state). The WTRU may use the WTRUcontext identity received as an outcome of RAN area update procedure ifapplicable and/or WTRU context identity received from source RAT. TheWTRU may perform a resume procedure and/or transition to CONNECTED stateto perform data transmission.

A WTRU may perform procedures defined for INACTIVE and/or Lightconnected operation in the target RAT, e.g. paging monitoring, systeminformation update monitoring, autonomous mobility, etc. The WTRU mayreceive a RAN paging message in the target RAT and/or transmit a pagingresponse to confirm the success of the mobility procedure. If the targetRRC state is CONNECTED state: the WTRU may transmit RRC connectionreconfiguration complete to the target cell. If the target RRC state isIDLE state: the WTRU may perform a tracking area update procedure in thetarget RAT (e.g., if the type of core network is different betweensource and target RAT). The WTRU might not perform any UL signalingtransmission as a result of mobility procedure, with the exception of atracking area update procedure. The WTRU may perform procedures definedfor IDLE mode operation in the target RAT, e.g. paging monitoring and/orsystem information update monitoring etc.

A WTRU may consider that the mobility procedure has failed if the WTRUcannot comply with one or more aspects of a received mobility-commandand/or the criteria for success cannot be met within a predefined timer(e.g., started when the mobility-command is received). Upon failure ofmobility procedure towards the target RAT, WTRU may take one or moreactions as a function of a target RRC state and/or source RRC state. Forexample, if the target RRC state is IDLE state, the WTRU may find asuitable cell in source RAT and/or camp on such cell. If the source RRCstate is CONNECTED, the WTRU may revert back to the configuration usedin the source cell and/or initiate the connection re-establishmentprocedure. If the source RRC state is INACTIVE and/or light connected,the WTRU may revert back to the configuration used in the source celland/or initiate the connection resume procedure. A connection resumemessage may carry the reason for failure of the mobility procedure.

A WTRU in INACTIVE state in NR, and/or Light connected state in LTE, asa result of autonomous mobility (e.g., reselection) to a cell of adifferent RAT (e.g., LTE and/or NR), may transition to a RRC stateapplicable to that RAT. For example, a WTRU may trigger autonomousmobility based on presence of a suitable cell in a high priority RATand/or based on quality of the current serving cell below a threshold.The WTRU may determine the RRC state applicable in the target cell basedon one or more of the following criteria: presence of radio resourceconfiguration applicable for the target RAT, type of core network,and/or relation between source cell and target cell to a logical area.

The presence of radio resource configuration applicable for the targetRAT: If the WTRU has a stored configuration applicable for the targetRAT (e.g., identity associated with WTRU context, bearer configurationfor target RAT, security context etc.), the WTRU may transition toLight-connected state (e.g., if LTE is target RAT) and/or INACTIVE state(e.g., if NR is target RAT). If the WTRU does not have a storedconfiguration applicable for the target RAT (e.g., identity associatedwith WTRU context, bearer configuration for target RAT, security contextetc.), the WTRU may transition to IDLE state in the target RAT and/orindicate release of RRC connection to higher layers. The WTRU mayconvert the radio resource configuration received in the source cell tobe applicable in the target RAT. For example, the WTRU may convert oneor more, or each, QoS flows in a NR RAT to DRB when transitioning to aLTE RAT, if LTE does not support QoS granularity at flow level.

Determining one or more types of core networks is described herein. TheWTRU may determine the type of core network associated with the targetcell from the system information. If the source cell and target cell areassociated with the same core network, the WTRU may transition toLight-connected state (e.g., if LTE is target RAT) and/or INACTIVE state(e.g., if NR is target RAT). If the source cell and target cell areassociated with a different core network, the WTRU may transition toIDLE state in the target RAT and/or indicate release of RRC connectionto higher layers. The WTRU may perform a tracking area update procedureapplicable for the core network associated with the target RAT. If thesource cell and target cell belong to a different CN level logical area(e.g., tracking area) and/or are associated with two different corecontrol plane entities, the WTRU may transition to IDLE state in thetarget RAT and/or indicate release of RRC connection to higher layers.The WTRU may perform a tracking area update procedure applicable for thecore network associated with the target RAT.

Relationships between a source cell and a target cell to a logical areaare described herein. For example, perhaps if the source cell and targetcell belong to the same RAN area, a WTRU may transition toLight-connected state (e.g., if LTE is target RAT) and/or INACTIVE state(e.g., if NR is target RAT). For example, perhaps if the source cell andtarget cell belong to a different RAN area, the WTRU may perform a RANarea update in the target cell, by transitioning to connected state ifdata transfer is not allowed in INACTIVE/Light-connected state.

User plane aspects of light connectivity may be provided. Layer 2processing with light connectivity may be provided. The terms layer 2configuration, layer 2 state and/or layer 2 context may be defined asfollows (e.g., for L2 handling in light connectivity) unless statedotherwise.

A Layer 2 configuration may include parameters that may be received by aWTRU and/or may be pre-defined for a WTRU. Parameters may stay constantfor the duration of a light connection unless changed by the networkand/or internally by the WTRU (e.g., based on changes in state and/orlink condition). For example, layer 2 configuration may include QoSconfiguration (e.g., flow and/or bearer configuration), logical,transport and/or physical channel configuration, resource configuration,and/or beam process configuration, etc.

A Layer 2 state may represent a snapshot of a layer 2 status that maychange over time. Status may include state variables, buffer status,timer status, outstanding feedback, triggers, received grants, headercompression context, etc. A Layer 2 context may include a combination oflayer 2 configuration and layer 2 state.

A layer 2 may be reset (e.g., a WTRU may forget some or all layer 2configuration and/or may delete the layer 2 state) for example, when aWTRU moves from connected to idle state. A WTRU may forget part of layer2 context such as a lower sub-layer of layer 2 (e.g., RLC/MAC), forexample, in case of connected mode when entering a target cell. WTRUhandling of layer 2 may be different for a light connected state for NR.A WTRU may determine the status of layer 2 during light connectedmobility scenarios. For example, a WTRU may determine the status oflayer 2 without interaction with the network.

NR may support diverse deployment scenarios, including a flexible splitof functionality between a central unit and a remote unit. A layer 2configuration for a WTRU may be determined, for example, by a centralcontrol function, by an edge control function and/or may be splitbetween central and edge control functions. A layer 2 state for a WTRUmay be maintained by a central unit, by remote unit, and/or may be splitbetween central and remote units.

A WTRU (e.g., when entering light connected state from a connectedstate) may, for example, completely reset layer 2 context, reset part oflayer 2 context or maintain a whole layer 2 context. A WTRU maydetermine how much layer 2 context to maintain, for example, based onone or more of the following: location, deployment, service/slice/flow,validity time and/or data transfer during light connectivity.

A WTRU may determine how much layer 2 context to maintain, for example,based on Location (e.g., within the same cell, within the same RAN PA,different RAN PA and/or different tracking area).

A WTRU may maintain layer 2 configuration and/or layer 2 state, forexample, when entering light connected state and/or remaining in thesame cell where the WTRU was in connected mode.

A WTRU may maintain a layer 2 configuration, but may reset the (e.g.,entire) layer 2 state and/or may reset (e.g., only) the state of lowersub-layers of layer 2, for example, while in light connected stateand/or entering a different cell within the same RAN PA.

A WTRU may maintain a layer 2 configuration, but may reset the (e.g.,entire) layer 2 state, for example, while in light connected stateand/or entering a different cell in a different RAN PA, but within thesame tracking area.

A WTRU may reset the (e.g., entire) layer 2 context, including layer 2configuration and/or layer 2 state, for example, while in lightconnected state and/or entering a different tracking area.

For example, WTRU mobility within a current RAN PA may be transparentfrom layer 2 perspective. A WTRU may consider layer 2 context to bevalid within the current RAN PA and/or may reset the layer 2 contextupon leaving layer 2 context.

A WTRU may determine how much layer 2 context to maintain, for example,based on Deployment (e.g., based on functional placement between acentral unit and a remote unit, based on reachability to a centralcontrol function, and/or based on type of connectivity (e.g., standaloneNR and/or multi-connectivity with another layer/RAT).

A WTRU may maintain a layer 2 state, for example, as a function ofreachability to a last serving edge control function before enteringlight connected state.

A WTRU may maintain a layer 2 configuration, for example, as a functionof reachability to a last serving central control function beforeentering light connected state.

A WTRU may determine how much layer 2 context to maintain, for example,based on Service/Slice/flow (e.g., based on latency, reliability, and/orinterruption time requirements of the service, such as differenthandling of layer 2 contexts associated with URLLC, eMBB and/or mMTC.).

A WTRU may reset (e.g., entire) layer 2 context associated with eMBBservice/slice/flow. A WTRU may maintain a layer 2 configuration, but mayreset the layer 2 state associated with mMTC service/slice/flow. A WTRUmay maintain a layer 2 state and/or a layer 2 configuration associatedwith URLLC service/slice/flow.

A WTRU may determine how much layer 2 context to maintain, for example,based on Validity time (e.g., WTRU handling of layer 2 context may be afunction of a validity timer).

A WTRU may maintain a layer 2 context across different cells, forexample, when contexts may be valid. This may be useful, for example,when a WTRU enters a previous serving cell before expiration of thevalidity timer. A combination of location and validity timers may beused. A validity timer may be stopped, for example, when a WTRU changeslocation before timer expiration.

A WTRU may store a layer 2 configuration up to a first validity timer. AWTRU may maintain a layer 2 state up to a second validity timer. A firstvalidity timer may be larger than a second validity timer.

A WTRU may determine how much layer 2 context to maintain, for example,based on data transfer during light connectivity. A WTRU handling oflayer 2 context may depend on whether data transfer may beallowed/configured/possible in light connectivity. For example, a WTRUmay retain a layer 2 configuration and/or a layer 2 state upon entryinto a light connected state, for example, when data transfer may beallowed in light connected state. A WTRU (e.g., when data transfer mightnot be allowed/configured/possible in light connectivity) may delete alayer 2 state, but may retain layer 2 configuration during entry tolight connected state.

A WTRU may re-use the status of a layer 2 context (e.g., parts of alayer 2 configuration and/or a layer 2 state that may have beenstored/maintained during the light connected state), for example, duringre-connection (e.g., transition from light connected to connectedstate).

A WTRU (e.g., when performing data transfer in light connected state)may consider a received layer 2 configuration applicable for a (e.g.,whole) RAN paging area. A WTRU may acquire and/or may apply a defaultservice/slice for data transfer in light connected state. For example, aWTRU may reset a layer 2 state for a (e.g., one or more, or each) streamof packet activity. For example, a stream of packet activity may bedetermined by the DRX state of the WTRU. A WTRU may retain a layer 2state, for example, while the WTRU stays in on-duration and/or whenthere may be active data transmission. A WTRU may perform partial layer2 reset upon entering DRX. A partial layer 2 reset may involve one ormore of the following: suspension of RLC/MAC timers, reset of RLC statevariables, flush of HARQ buffer, initialization of logical channelprioritization, etc. A WTRU (e.g., upon waking up from DRX) may apply alayer 2 configuration, e.g., including security configuration, keyderivation, etc. Use of a common layer 2 configuration and/or simplifiedlayer 2 state handling may reduce X2 signaling to synchronize WTRU layer2 state with a plurality of transmission points.

Data transfer may be provided during light connectivity. A WTRU mayperform data transfer without leaving light connected state. A WTRU mayuse configured resources (e.g., grant-less and/or periodic resources)and/or may acquire resources (e.g., using a random access and/or ascheduling request). For example, a WTRU may transmit control planemessages while in light connected state, but may transition to connectedstate, for example, to transmit user plane data. For example, a WTRU maydetermine to transition to a connected state as a function of PDU size,type of PDU, and/or other criteria described in (e.g., restricted) datarules. A WTRU may perform a RAN paging area update without leaving lightconnected state. For example, a WTRU may perform RACH, send an RRCmessage for RAN PA update in msg3, etc. A WTRU may receive successfulacknowledgment from a network, e.g., in a msg4 and/or similar. A WTRUmay perform a RAN PA update using one or more of the data transfermechanisms while staying in INACTIVE state. A RAN PA update proceduremight not include a change in WTRU state. This approach may eliminatesending a connection request and/or subsequent overhead associated withestablishment and/or release of a connection. A WTRU may avoid randomaccess and/or may (e.g., directly) perform a RAN paging area update, forexample, using a separate access method (e.g., non-orthogonal access,RSMA, CB-PUSCH, asynchronous access and/or similar).

Different levels of data transfer may be allowed/configured for a WTRUin light connectivity, for example, restricted data transfer and/or nodata transfer.

A level of data transfer may be restricted data transfer. A WTRU mayperform data transfer without leaving light connected state. A WTRU mayperform autonomous mobility and/or may be tracked at RAN PA granularity.A WTRU may perform QoS enforcement during light connected state. A WTRUmay perform QoS enforcement, for example, by restricting data transferactivity during light connected state. The WTRU may initiate a procedureto (re-)establish an RRC connection with the network, perhaps forexample when data becomes available for uplink transmission, but doesnot otherwise match the criteria for transmission while remaining in thecurrent state (e.g., the amount of data exceeds, and/or its type doesnot match) the restriction criteria). Restrictions may be in terms ofone or more criteria individually and/or in any combination.

Restriction criteria (e.g., for data transfer) may comprise allowed datarate and/or data volume over a time period. For example, a WTRU may beconfigured with maximum data volume over a time period. A WTRU maytransition to connected state, for example, when actual data volume mayexceed a preconfigured threshold. A WTRU may be configured with a buffersize threshold indicating allowed data volume for transmission withoutinitiating a L3 procedure (e.g., a (re-) connection request) that maylead to a state transition. A WTRU may measure a transmitted data volumemetric during light connected state. A metric may be maintained at theWTRU across cell changes, e.g., to avoid extensive network coordination.

For example, a WTRU may be configured to perform single shot datatransmission in light connected state. A WTRU may perform data transferin light connected state if the number of data PDUs to be transmitted isbelow a preconfigured number (e.g., 1). A WTRU may perform data transferin light connected state if the data PDU fits within the availableand/or configured UL resources.

For example, a WTRU may be configured to perform initial transmission ofdata in light connected state. A WTRU may stay in the light connectedstate if an acknowledgement is received from the network. A WTRU maytransition to connected state if a configured number of retransmissionsare exceeded and/or if a negative acknowledgement is received.

Restriction criteria (e.g., for data transfer) may comprise validitytime associated with configured resources. A WTRU may consider thevalidity of configured common and/or dedicated resources as anindication to perform data transfer. For example, a WTRU may performdata transfer in light connected state while the validity timer ofcommon and/or dedicated resources may be running.

Restriction criteria (e.g., for data transfer) may comprise elapsed timefrom the last network interaction. A WTRU may perform data transferwhile a preconfigured time might not be elapsed from previous networkinteraction. Network interaction may be a signaling transaction (e.g.,transmission/reception of signaling message such as a RAN PA update)and/or data transaction (e.g., transmission/reception of data PDU).Elapsed time from a last network transaction may be associated with a ULtime alignment timer.

Restriction criteria (e.g., for data transfer) may comprise a type ofservice. For example, data belonging to a (e.g., specific)service/slice/flow may be allowed (e.g., URLLC and/or MTC type oftraffic may be allowed) while a WTRU may transition to connected statefor eMBB. For example, such restrictions may be realized as datatransfer without state transition applicable only for subset of DRBs.

Restriction criteria (e.g., for data transfer) may comprise a directionof transfer. For example, a DL transfer and/or feedback may be allowed.A WTRU may transition to connected mode for UL data transfer.

Restriction criteria (e.g., for data transfer) may comprise a type ofPDU. For example, a WTRU may restrict data transfer to type of PDU(e.g., L3 signaling L3 and/or NAS signaling may be allowed. A WTRU maytransition to connected state for data PDU). A restriction may beenforced at a radio bearer/flow level. For example, a data transfer inlight connected state may be restricted to signaling radio bearers/flow.

Restriction criteria (e.g., for data transfer) may comprise a location.For example, a WTRU may be allowed to perform data transfer while withina cell and/or RAN paging area where it entered light connected state.

Restriction criteria (e.g., for data transfer) may comprise an accesscontrol. For example, a WTRU may be configured to determine thepossibility of data transfer while in INACTIVE state based on an accesscontrol indication from the network. An access control indication may bea function of WTRU state, for e.g., a WTRU may be configured withdifferent access control parameters for idle and/or INACTIVE states.Access control may be enforced by broadcast signaling. The accesscontrol indication may restrict the use of data transfer in the presenceof the indication. The access control indication may specify a period oftime over which data transmission may (e.g., should) be delayed. TheWTRU may probabilistically (e.g., based on random selection) determinewhether and/or an amount of time to delay/avoid data transmission in anINACTIVE state based on a comparison of the randomly selected value withthe access control indication.

Restriction criteria (e.g., for data transfer) may be based on one ormore other criteria. A WTRU may perform a data transfer without leavinga light connected state, for example, when received higher layer datamay be allowed by other restriction criteria. A WTRU may trigger atransition to a connected state and/or may (e.g., subsequently) transmitdata to the network, for example, when higher layer data may berestricted by other criteria.

A level of data transfer may be no data transfer. For example, datatransfer might not be allowed in light connected state. A WTRU maytransition to connected state to perform data transfer.

A WTRU may be configured with common and/or dedicated resources toperform data transfer while staying in a light connected state. Commonresources associated with light connectivity may be provisioned byconfiguration that may be applicable to more than one cell. For example,common resources and/or dedicated resources may be grant-less resources.A WTRU may perform contention based data transfer, for example, whenresources may be common to a plurality of WTRUs. For example, resourcesmay be semi-static resources. For example, resources may be asynchronousresources, wherein a WTRU might not be time synchronized on an UL to uselight connectivity resources. A WTRU may consider common and/ordedicated resources to be associated (e.g., only) with a serving cellwhere the WTRU entered light connected state. A WTRU may release and/orstop using resources, for example, upon leaving a serving cell. A WTRUmay consider common and/or dedicated resources to be multi-cell (e.g.,associated with a RAN paging area). A WTRU may consider resources to bevalid while a WTRU may be in light connected state and/or within a RANpaging area where the WTRU entered light connected state. A WTRU mayperform cell update upon a (e.g., one or more, or each) cell change, forexample, when resources may be associated with RAN paging area. Commonand/or dedicated resources may be associated with validity time.

The WTRU in RRC INACTIVE state (e.g., light connected and/or equivalent)may transmit a single transport block that may include an amount ofdata. For example, the amount of data that the WTRU may transmit in RRCINACTIVE state may be an amount of data no larger than a specificthreshold x. For example, transmission in RRC INACTIVE state may furtherinclude an identity of the WTRU and/or of the WTRU context. For example,such amount of data x may be an aspect of the WTRU configuration (e.g.,such as a value indicated by L3/RRC signaling during a configurationprocedure, a reconfiguration procedure, a RAR message, and/or in a RANPA update response). A WTRU may be configured with the value x as athreshold associated with WTRU buffer size. For example, the WTRU maydetermine the value of x as a function of downlink signal quality. Forexample, such amount of data x may represent and/or corresponds to userplane data, but not control plane data (e.g., control plane data mightnot count toward the data limit for transmission in RRC INACTIVE). Forexample, data transmission in RRC INACTIVE may include an amount y ofcontrol plane data such as generated for the purpose of reportingmeasurements, RAN PA update, and/or the like. For example, the WTRU maytransmit such amount x of data within a certain period of time t. Suchperiod of time t may be an aspect of the WTRU configuration (e.g., suchas a value indicated by L3/RRC signaling during a configuration and/or areconfiguration procedure).

For example, the WTRU may start a timer using value t one or more, oreach, time it performs a transmission when in the RRC INACTIVE state(e.g., light connected and/or equivalent). For example, the WTRU may beconfigured to refrain from performing further transmission in the RRCINACTIVE state while the timer running. For example, the WTRU may startthe timer for transmissions that contain user plane data, but fortransmission that have just control plane data. In this manner, thetimer may be used to enable transmission of a specific amount of userplane data without involving a L3/RRC state change and/or perhaps theuse of L3/RRC signaling (e.g., except possibly to convey an identityassociated with the WTRU and/or the WTRU’s context). This may be usefulto enable transmission of control plane data such as measurements and/orother uplink control information without involving any L3/RRC statechange. Such transmission may be performed as part of a random accessprocedure. For example, such transmission may be performed using aresource associated with the transmission of a preamble, with acontention-based grant and/or with a grant received as part of aresponse to the transmission of a preamble. For example, suchtransmission may be included in msg3 (and/or equivalent) of a randomaccess procedure.

Initial access messages may refer to a message exchange between a WTRUand a network, for example, before the WTRU enters a fully connectedstate. For example, initial access messages may include MSG1 (e.g.,transmission on a random access channel and/or a transmission on acontention based channel and/or the like), MSG3 (e.g., a higher layermessage on a signaling bearer/flow and/or a data PDU on a databearer/flow), MSG2/MSG4 (e.g., an indication from a network where a WTRUmay obtain a timing advance, a temporary identity, UL resource and/or anindication to enter connected state).

Data transmission may be performed, for example, using one or moreinitial access messages. A WTRU may perform data transfer in lightconnected state without entering a fully connected sate. Performing datatransfer within light connected state may reduce overhead for small dataPDU transmissions. Small data transmissions may include, for example,background traffic in smartphones, sporadic signaling messages, a RAN PAupdate message, etc.

A WTRU in light connected state may use one or more initial accessmessages to transmit a data PDU without leaving light connected state.

Data transmission may be performed, for example, using a random accessresource. A WTRU may use one or more characteristics/properties of arandom access resource to perform data transfer in light connectedstate.

For example, a WTRU may select a random access resource that may belongto a random access channel format. A random access channel format mayallow for data transmission along with random access preambletransmission. A predefined relation in terms of time and/or frequencymay exist between a data payload and a preamble sequence. A randomaccess channel format may (e.g., also) define a modulation and/or codingscheme to be applied for data transmissions. A WTRU may be configuredwith one or more random access channel formats with flexible and/orconfigurable sizes of payloads and/or MCS and/or preamble lengths,and/or presence/characteristics of synchronization signal and/orpresence/characteristics of demodulation reference signal and/or cyclicprefix lengths and/or guard period lengths etc.

For example, a WTRU may determine whether to perform data transmissionusing a random-access resource and/or to perform random access to enterconnected mode based on a size of the data PDU. For example, a WTRU mayperform data transmission using a random access resource that may allowfor a payload size greater than or equal to the size of a data PDU. AWTRU may (e.g., otherwise) select a random access resource without adata payload, e.g., for a subsequent reconnection/resume procedure.

For example, a WTRU may determine whether to perform data transmissionusing a random access resource and/or to perform random access to enterconnected mode based on the quality of the serving cell. For example, anRSRP/RSRQ associated with a serving cell may be above a threshold and/ora path loss of a serving cell may be below a threshold. A WTRU mayperform data transmission using an appropriate random access resource.

For example, a WTRU may select a random access resource for datatransmission based on the status of timing alignment. For example, aWTRU may select a random access resource with a longer preamble and/or alonger cyclic prefix, e.g., when the WTRU may no longer be timingaligned on the uplink. For example, a WTRU may select a random accessresource with a shorter preamble and/or shorter cyclic prefix, e.g.,when the WTRU has a valid timing advance.

For example, a WTRU may transmit demodulation reference signals whenperforming data transmission on a random access resource. For example, aWTRU may (e.g., also) transmit a demodulation reference signalmultiplexed with data in time and/or frequency with the data payload.

For example, a WTRU may perform data transmissions on a plurality ofrandom access resources. For example, a repetition factor may beassociated with a RACH resource. A plurality of RACH resources that maybe separated by time and/or frequency may be grouped together. Forexample, a WTRU may repeat data PDU transmissions, for example, bycycling through different redundancy versions in different RACHresources that may belong to a RACH resource group.

Data transmission may be performed on a contention based resource. Forexample, a WTRU may use a contention based resource to perform datatransfer in light connected state.

One or more procedures for a random access based resource may beapplicable to a contention based resource (e.g., the term random accessresource may be replaced with the term contention based resource).

For example, a WTRU may determine a configuration (e.g., time/frequencyresources) of a contention based resource based on a DL grant associateda predefined RNTI.

For example, a WTRU may be configured with a modulation and/or codingscheme that may be used for data transmission in a contention basedresource. A WTRU may use a predefined MCS scheme and/or a MCS schemethat may be dynamically indicated in a DL grant associated with acontention based resource.

A WTRU may (e.g., when a contention based resource and/or a randomaccess resource are available) determine which resource to use, forexample, based on one or more of type of service, size of data PDU,status of UL timing advance, link quality, path loss metric, channeloccupancy, etc. For example, a WTRU may use a contention based resource,for example, when it has a valid UL timing advance.

A WTRU may fall back to a random-access channel, for example, when acontention based resource might not be used, when an acknowledgement fora data PDU transmission might not be received within a predefined timeinterval, and/or when a number of retransmissions on a contention basedresource may exceed a threshold.

WTRU identity may be associated with a data transmission. A WTRU mayindicate an identity, for example, when performing data transmission ina random access resource and/or a contention based resource. Forexample, an identity may uniquely identify a WTRU and/or WTRU contextassociated with a UL data transmission.

For example, a WTRU may indicate an identity using a choice of randomaccess preamble. For example, a WTRU may be configured with a dedicatedrandom access preamble. For example, a dedicated sequence may be uniquewithin a RAN paging area.

For example, a WTRU may indicate an identity using a synchronizationsignal sequence, a demodulation reference signal sequence and/or asignature sequence. For example, a WTRU may be configured with adedicated signal sequence. A dedicated sequence may be unique within aRAN paging area.

For example, a WTRU may indicate an identity using a MAC control elementthat may be included with a random access payload.

For example, a WTRU may include a WTRU identity with data (e.g., in MACPDU), for example, when performing data transmission in light connectedstate.

For example, a WTRU may include a WTRU identity with a reconnectionrequest and/or similar (e.g., in a RRC PDU), for example, whentransitioning to a fully connected state for data transfer.

A WTRU may determine the type and/or size of WTRU identity based onwhether data transfer is performed within the same anchor eNB and/or adifferent eNB in the same RAN area. For example, the WTRU may use ashorter identity within the same anchor eNB. A shorter identity may beexplicitly assigned by the eNB (e.g., a RNTI) and/or a function of WTRUidentity in INACTIVE state.

WTRU assistance may be provided for data transfer in light connectedstate. A WTRU in light connected state may use one or more initialaccess messages to convey an indication to the network. An indicationmay include, for example, a WTRU’s desire to perform data transferwithout a transition (e.g., to light connected state) and/or the size ofgrant to transmit a data PDU in light connected state.

For example, a WTRU may indicate the size of grant (e.g., that may beused to transmit a data PDU in light connected state) in the payload ofa random access resource. For example, a WTRU may include a grant sizein a MAC control element in a random access payload and/or a contentionbased resource.

For example, a WTRU may indicate a (e.g., need for) data transmission inlight connected state, for example, using a choice of preamble sequenceand/or other characteristic(s) of a random access resource. A choice mayindicate a WTRU’s desire to transmit data without leaving a connectedstate and/or may assist a network in determining a grant for thetransmission.

A WTRU may handle MSG2 (e.g., RAR). A WTRU may declare a successfulcontention resolution, for example, when a WTRU ID included with a datatransmission in MSG1 (e.g., RACH and/or contention based resource) maybe (e.g., is) present in MSG2.

A WTRU may perform data retransmission using, for example, a randomaccess resource and/or a contention based resource, e.g., when a WTRU IDmight not be present in MSG2 and/or when the WTRU might not havereceived a MSG2 within a predefined time interval.

For example, a WTRU may receive in MSG2 an acknowledgement for a dataPDU transmitted in MSG1. For example, a WTRU may determine a status ofan uplink (UL) data transmission based on presence of a grant in MSG2.

A WTRU may determine that data transmitted in MSG1 was receivedsuccessfully, for example, when MSG2 has a WTRU ID and/or no further ULgrant. A WTRU may determine that data may be retransmitted, for example,when MSG2 has a valid WTRU ID and/or an UL grant.

For example, a WTRU may receive an indication in MSG2 to transition tofully connected state for data transmission. A WTRU may use a UL grantin MSG2 to perform a reconnection procedure.

For example, a WTRU may receive a UL grant in MSG2 for a contentionbased resource. A WTRU may perform (re-)transmission on a contentionbased resource. The WTRU may adjust the UL timing based on the timingadvance command received in MSG2.

For example, a WTRU may receive in MSG2 a notification to stop using acontention based resource for a predefined time period. A WTRU mayreceive a notification, for example, when a contention based resourcemay be (e.g., is) overloaded.

Data transmission may be performed using MSG3. For example, a WTRU mayperform data transmission using a MSG3 while staying in light connectedstate.

A WTRU may receive in MSG2 an indication to perform data transfer usingMSG3 without entering fully connected state.

A WTRU may autonomously determine whether to transmit data in MSG3and/or a reconnection message in MSG3 in MSG3, for example, based on thesize of UL grant received in MGS2.

A WTRU may directly transmit data PDU in MSG3, for example, when a ULgrant may be greater than or equal to a data PDU plus headers.

A WTRU may perform a reconnection procedure using MSG3 and/or transitionto connected state for data transmission, for example, when a UL grantreceived in MSG2 is not sufficient for data PDU transmission.

For example, a WTRU may include a reconnection message in MSG3 and/orbased on remaining available resource, the WTRU may also include dataPDU in the MSG3.

A WTRU may determine whether to transmit data in MSG3 and/or areconnection message in MSG3, for example, based on the status ofcontention resolution.

For example, a WTRU may directly transmit data PDU in MSG3, for example,when the WTRU determines that contention is resolved based on indicationand/or presence of its identity in MSG2.

For example, a WTRU may transmit a higher layer signaling message, e.g.,a reconnection message, if the WTRU cannot unambiguously determine thatthe contention is resolved based on MSG2 reception.

A WTRU may indicate (e.g., using MAC headers) the presence of a data PDUin an MSG3 transmission (e.g., including a LCID associated with the dataPDU).

A WTRU may include an identity associated with a WTRU in light connectedstate and/or an identity associated with a WTRU context, for example,when transmitting data in MSG3.

A WTRU may apply a preconfigured security configuration (e.g., securitykey, security algorithm) to cipher a data PDU, for example, when a WTRUtransmits data in an initial access message.

A WTRU might not perform segmentation of data PDUs, for example, whenusing initial access messages for data transfer.

A WTRU may use a reconnection procedure to enter a connected stateand/or (e.g., subsequently) perform unrestricted data transfer.

A WTRU may process MSG4, for example, MSG4 may be received following ULtransmission and/or transmission of MSG3. A WTRU may receive areconfiguration message as part of MSG4 and/or perform reconfigurationof its RRC parameters related to light connected behavior. Suchparameters may include any parameter and/or subset of parametersprovided in the initial light connected configuration, such as, but notincluding, security parameters, thresholds/rules defining the decisionto move to connected, new WTRU ID, etc.

In one example, the WTRU may receive a new WTRU ID to be used fortransmission of data and/or reception of paging messages. The WTRU mayapply this new WTRU ID for future transmissions, in calculation of itspaging occasions, and/or in processing PDCCH for reception on thecontrol channel.

For example, the WTRU may receive a new security context, such as any ofnew keys and/or any parameters required/useful for computation of newkeys, such as NCC. The WTRU may compute a new (e.g. fresh and/orpreviously unused) set of keys based on the NCC provided in MSG4 and/ormay utilize the new keys for ciphering and/or integrity protection infuture UL transmissions.

A WTRU may further receive such reconfiguration, and/or indication toinitiate reconfiguration in a DL message following MSG4, such as duringan extended scheduling period.

A WTRU may receive, in MSG4, an indication to initiate an RRC procedurewhich may reconfigure the WTRU and/or move the WTRU to connected mode.

For example, the WTRU may receive an indication in MSG4, and/or insubsequent scheduling, an indication from the network to initiate aresume procedure and/or similar procedure to perform transition toconnected mode.

For example, the WTRU may receive an indication in MSG4, and/or insubsequent scheduling, an indication from the network to initiate arequest for reconfiguration. Such request may be similar to a resumerequest, with a response providing reconfiguration parameters.

For example, the WTRU in an INACTIVE state may maintain a first securitycontext. A first security context may be applicable to transmission whenin the INACTIVE state. A first security context may include one or moresecurity keys, security algorithms, and/or sequencing information (e.g.,a COUNT value for bearers applicable to the INACTIVE state). Sequencinginformation may be specific to the INACTIVE state. Sequencinginformation may be common for one or more, or all transmissionsassociated with the concerned bearer (e.g., independently of what statethe WTRU is when a transmission is performed). Security keys may includea key for the integrity protection of RRC signaling(K_(RRCinactive_int)), one for the ciphering of RRC signaling(K_(RRCinactive_enc)), and/or one for the ciphering of user data(K_(UPinactive_enc)). Security context may be associated to the INACTIVEstate only. The WTRU may perform management of security context as afunction of the RAN paging area. For example, the WTRU may derive a newset of keys for the first security context upon a change of RAN pagingarea (e.g. the security context may be paging-area specific). A separatekey K_(p)__(area) may be used for the INACTIVE state. A key K_(p_area)may derived from the K_(ASME) key taken into use with the latestsuccessful NAS security mode command/activation (SMC) procedure. A keyK_(p_area) may be derived from the key used for the CONNECTED state(K_(eNB)) and/or a RAN paging area counter may be used to ensurefreshness. A WTRU may derive new keys as part of the RAN-paging areaupdate procedure.

A RAN-paging area update procedure may include an exchange ofsecurity-related parameters (e.g., such as a next area chaining count(NACC) which may be similar to the legacy next hop chaining countparameter NCC (and/or NHCC) for the CONNECTED state). A RAN-paging areaupdate procedure may also indicate new integrity and/or cipheringalgorithms (e.g., security algorithms may be area-specific). A WTRU mayuse the integrity protection and/or ciphering of the first message (forUL and/or DL transmissions) for transmission in the INACTIVE state basedon the security configuration last updated. A WTRU use the integrityprotection and/or ciphering of the RRC message for a paging-area updatebased on the security configuration used prior to the paging-area updateprocedure. From the network perspective, security may be applied basedon the “source” paging area. An explicit key change indication may bereceived upon RAN-paging area update and/or indicate whether the WTRUmay use the keys associated with the K_(ASME) key taken into use withthe latest successful NAS security mode command/activation (SMC)procedure.

A first security context may be applied to transmissions until a secondsecurity context may be used and/or activated. For example, the WTRU mayuse ciphering of a data message for a transmission while in the INACTIVEstate using the first security context. The WTRU may use the firstsecurity context for subsequent such transmissions. The WTRU may use theintegrity protection and/or ciphering of the RRC message from thenetwork while in the INACTIVE state using the first security context.The WTRU may activate (and/or reactivate) a second security context fromthe reception of such RRC message (e.g., associated to a connectionestablishment procedure). A WTRU may use the integrity protection and/orciphering of the RRC message for initiating a transition to theCONNECTED state and/or receive the response from the network while inthe INACTIVE state using the first security context. The WTRU mayactivate (and/or reactivate) a second security context from thereception of the response. Activation of a second security context maycorrespond to a transition to the CONNECTED state. A second securitycontext may correspond to the AS security context also applicable fortransmission while in the CONNECTED state (e.g., using four AS keys(K_(eNB), K_(RRCint), K_(RRCenc) and/or K_(UPenc)) and/or applicablesecurity algorithms).

Systems, methods, and/or instrumentalities have been disclosed for lightconnectivity and/or autonomous mobility. A WTRU may, for example, havean inactive/idle mode, a light connected/loosely connected/Inactive modeand/or a connected/fully connected/Active mode. A WTRU in lightconnected mode may have a WTRU context stored in a RAN. A WTRU mayperform an area monitoring procedure while in light connected state. AWTRU may engage in autonomous mobility during light connectivity. A WTRUmay move within a logical area (e.g., a RAN paging area) withoutnotifying the network, but may provide notice when it has moved outsidea logical area (e.g., update RAN paging area). Mobility in lightconnected state may be network controlled (e.g., to enable handover whendata transfer may be allowed and/or ongoing).

A WTRU may be reachable during a light connectivity state. A WTRU mayengage in autonomous mobility during light connectivity. A WTRU mayperform data transfer without leaving light connected state. A WTRU mayimplicitly transition to a light connectivity state. A network mayinitiate a light connectivity state. A transition from inactive to lightconnectivity may reduce signaling overhead and/or latency/delays thatmay otherwise occur before a WTRU may perform a first transmission inactive mode. A WTRU may transition to connected mode with low latencyand/or low overhead. A WTRU in a light connected mode may perform a datatransfer without entering an active mode, for example, using one or moreinitial access messages between the WTRU and/or the network before theWTRU enters the active mode.

In view of the techniques described herein, FIG. 2 illustrates anexample technique of a WTRU engaging in UL data transfer in an INACTIVEstate and/or a CONNECTED state. At 2000, the WTRU may be triggered(e.g., implicitly and/or explicitly) to enter an INACTIVE state. At2002, the WTRU may determine that UL data is to be transmitted. At 2004,perhaps upon consideration of one or more factors as described herein,such as the size of the UL data relative to a threshold, the WTRU maysend the UL data to TRP2 while in the INACTIVE state, else/and/or, at2006, after entering a CONNECTED state. For example, at 2004, the WTRUmay transfer the UL data in the INACTIVE state in consideration of oneor more of, but not limited to, the following factors: if thesize/amount of the UL data is less than a threshold; a size of anavailable UL grant (e.g., relative to the size/amount of the UL data) ;a location of the WTRU (e.g., an absolute location/specific area and/ora location relative to the TRP1 and/or TRP2); and/or a logical channel(LCH) (e.g., identity and/or availability) for which data becomesavailable, etc.

For example, at 2004, the WTRU may transfer the UL data in the INACTIVEstate in consideration of one or more of: a determination that an amountof the UL data is less than a predetermined threshold; a determinationthat a size of an available UL grant can accommodate the amount of theUL data; a determination that the WTRU is within at least one of: aspecified area, or a predetermined area; and/or a determination that alogical channel identity associated with the UL data is at least one of:available, or applicable.

In view of the techniques described herein, FIG. 3 illustrates anexample technique of a WTRU engaging UL data transfer in an INACTIVEstate and/or CONNECTED state. At 3000, the WTRU may be triggered (e.g.,implicitly and/or explicitly) to enter an INACTIVE state. At 3002, theWTRU may (e.g., autonomously) determine to engage in mobility betweenTRP1 and TRP2. At 3003, the WTRU may determine that UL data is to betransmitted. At 3004, perhaps upon consideration one or more factors asdescribed herein, such as the size of the UL data relative to athreshold, the WTRU may send the UL data to TRP2 while in the INACTIVEstate, else/and/or, at 3006, after entering a CONNECTED state. Forexample, at 3004, the WTRU may transfer the UL data in the INACTIVEstate in consideration of one or more of, but not limited to, thefollowing factors: if the size/amount of the UL data is less than athreshold; a size of an available UL grant (e.g., relative to thesize/amount of the UL data); a location of the WTRU (e.g., an absolutelocation/specific area and/or a location relative to the TRP1 and/orTRP2); and/or a logical channel (LCH) (e.g., identity and/oravailability) for which data becomes available, etc. At 3008, the WTRUmay determine and/or apply at least one security level as describedherein, before the UL data is transmitted in the INACTIVE state.

For example, at 3004, the WTRU may transfer the UL data in the INACTIVEstate in consideration of one or more of: a determination that an amountof the UL data is less than a predetermined threshold; a determinationthat a size of an available UL grant can accommodate the amount of theUL data; a determination that the WTRU is within at least one of: aspecified area, or a predetermined area; and/or a determination that alogical channel identity associated with the UL data is at least one of:available, or applicable.

The processes and/or instrumentalities described herein may apply in anycombination, may apply to other wireless technologies, and/or for otherservices.

A WTRU may refer to an identity of the physical device, and/or to theuser’s identity such as subscription related identities, e.g., MSISDN,SIP URI, etc. WTRU may refer to application-based identities, e.g., usernames that may be used per application.

A WTRU may be configured with a different transmission profile for datatransfer in INACTIVE state. The transmission profile may include one ormore of the following: access type; access resource; and/or messagetype. A WTRU may be configured with plurality of access types for datatransfer in INACTIVE state (e.g., 2-step random access, 4-step randomaccess, contention based access, grant-less access, scheduled accessetc.). A WTRU may be configured with plurality of resources in timeand/or frequency and/or code associated with one or more, or each,access type. A WTRU may be configured with data transfer in MSG1, MSG3,and/or a subsequent message. A WTRU may determine if the messagecarrying data is/has multiplexed zero or more RRC messages.

A WTRU may determine a specific transmission profile for an initial datatransmission attempt. For example, the WTRU may determine the datatransmission profile as a function of one or more of the following: WTRUbuffer size threshold, serving cell quality, status of WTRU UL timingalignment, WTRU location (e.g. in the anchor eNB, different eNB in thesame RAN area etc.), availability of resources associated with thetransmission profile (e.g., earliest occurring resource in a timeinterval), quality of service associated with the data, WTRU identity(e.g., WTRU may select access resource as a function of WTRU identity inINACTIVE state) etc.

A WTRU may be configured to perform a pre-defined number ofretransmissions with the same transmission profile. The WTRU may switchto a different transmission profile based on the status of previous datatransmission, e.g., success or failure data transmission with a previoustransmission profile and/or based on an explicit indication in aresponse message from the network.

A WTRU may be configured to report the statistics associated with theusage of different transmission profiles. For example, a WTRU may keeptrack of number of failures/transmission attempts for one or more, oreach, transmission profile. A WTRU may report such statistics associatedwith data transmission in INACTIVE state to the network. A WTRU mayreport such statistics upon entering connected state. This may aid thenetwork configure access resources and/or WTRU buffer thresholds forresource utilization.

WTRU behavior during an extended scheduling period in inactive state maybe provided. For example, an extended scheduling period in NR-INACTIVEmay be provided. An initial transmission in INACTIVE state may triggerone or more subsequent transmissions. For example, such subsequenttransmission may include one or more of: acknowledgements from radioprotocol layers; higher protocol layers; one or more response PDUs fromapplication layer; one or more response packets from radio protocollayers (e.g., for control messages); and/or subsequent arrival of one ormore data PDUs in the same direction as initial transmission. Deliveryof subsequent DL transmission may be delayed if the WTRU is reachableonly during paging occasions after initial UL data transmission.Delivery of subsequent UL transmissions may be delayed if the WTRUperforms a subsequent UL transmission on channels that involvecontention, e.g., RACH and/or msg3 and/or any other contention basedchannel, perhaps if the contention may have (e.g., already) beenresolved during the initial transmission.

A data transfer method that supports transmission of more than one TB inthe downlink and/or in the uplink while in the RRC NR-INACTIVE state maybe provided. A WTRU, upon performing initial transmission using anyaccess method, may enter an extended scheduling period.

The WTRU in NR-INACTIVE state may initiate the random-access procedure,for example, in response to a received paging message and/or because new(e.g., UL) data becomes available for transmission. The WTRU maygenerate applicable L3 message (and/or L2 message) e.g., including anidentity of the WTRU and/or of the WTRU’s context if the logicalchannel(s) / bearer(s) for which new data is available for transmissionis applicable/available for data transfer while NR-INACTIVE state. TheWTRU may initiate a L3 procedure to move to a connected state, e.g., aconnection and/or a reconnection request.

The usefulness/need for extended scheduling may be signaled/indicated.Initially, the WTRU in NR-INACTIVE may determine that there is new dataavailable for transmission. The WTRU may generate a BSR that includesdata available for transmission in the WTRU’s buffer. The BSR may beonly for logical channels / bearers for which such transmission methodis applicable. The WTRU may include such BSR in the first transmission(e.g., msg3) following the reception of a first uplink grant (e.g. inRAR); possibly, only if the WTRU cannot accommodate one or more, or alldata being reported in the BSR in the corresponding TB.

While the data transfer procedure is ongoing, the WTRU in NR-INACTIVEmay determine that there is a RACH procedure, a data transfer, and/or anextended scheduling period ongoing. The WTRU may determine that there isnew data available for transmission applicable to such data transfermethod. The WTRU may include a BSR in the earliest possible uplinktransmission. The WTRU may initiate, and/or restart (e.g., by performinga new preamble transmission) a new random access procedure if itdetermines that the total amount of data included in one or more, or allTBs for which the WTRU has already assembled a MAC PDU and/or initiateda first (e.g., HARQ) transmission is equal or less than the total amountof data last reported e.g., in the last transmitted BSR and/or since theWTRU has received a positive HARQ feedback for the transmission thatincluded such BSR.

The WTRU may report a certain level (e.g., one of a finite set ofvalues) of data available for transmission as a function of a selectionof PRACH resources (e.g., preamble value, preamble group, PRACH resourcein time and/or frequency, preamble duration, numerology and/or the like)for the transmission of a preamble as described (e.g., instead of a BSRas described).

The WTRU may (e.g., implicitly) indicate certain level (e.g., one of afinite set of values) of data available for transmission and/or anindication that additional scheduling resources may be useful as afunction of a selection of a grant e.g., one out of a plurality (e.g.,two grants) of grants e.g., received in a RAR (and/or in a pluralitythereof) for the transmission of MSG3. The gNB may perform blinddecoding of transmission accordingly.

Scheduling opportunities may be determined. The WTRU may receive anindication in a downlink transmission that scheduling occasions may beavailable for a certain period of time. Such period of time may extendbeyond the successful reception of the last message associated with theaccess method (e.g., beyond the reception of msg2/4 in case of a 2-stepRACH procedure, beyond the reception of msg2 in case of acontention-free RACH procedure, and/or beyond msg4 in case of acontention-based RACH procedure, etc.). For example, such indication maybe received in a RAR response, in msg4, and/or based on status ofun-sustained data transfer. Such indication may correspond to a timervalue e.g., the WTRU may receive an index to a finite set of values of agiven time unit e.g., a frame, a subframe, a slot, a mini-slot, a TTI, aPDCCH opportunity, and/or a value in ms. A WTRU may determine the indexbased on adjusting the periodicity of RAN paging cycle and/or WTRUidentity in INACTIVE state.

The WTRU may start a timer Tschext with the received value. The WTRU maythen monitor the applicable control channel(s) e.g., for DCI(s) on PDCCHwhile the timer is running. The WTRU may restart the timer when itsuccessfully decodes control information (e.g., for a certain type ofcontrol information (e.g., a DCI associated with the WTRU’s identity, asearch space, a set of resources, etc.). The WTRU may update the timervalue according to the applicable time unit e.g., every lapse of aframe, a subframe, a slot, a mini-slot, a TTI, a PDCCH opportunity,and/or a value in ms.

A WTRU in an extended scheduling period may be configured to monitor thecontrol channel for a WTRU identity, for example, the WTRU identity maybe a function of WTRU identity associated with INACTIVE state and/or atemporary identity assigned during an access procedure (e.g., a RNTI).

A WTRU in an extended scheduling period may continue monitoring for RANpaging messages, e.g., if the RAN paging occasions occur during theextended scheduling period.

Procedures for the expiration of extended scheduling period may beprovided. The WTRU may stop monitoring for control information when thetimer expires and/or is no longer running. The WTRU may stop the timerwhen it initiates a random access procedure. The WTRU may stop the timerwhen it initiates a transition to a state different than the NR-INACTIVEstate. The WTRU may stop the timer upon autonomous mobility event, e.g.,a cell change. The WTRU may stop the timer when it receives an explicitindication from the network. The WTRU may be configured to stop thetimer when one or more, or all, UL buffers are empty. For example, theWTRU may be configured to stop the timer when one or more (or all) ULbuffers are empty for a determined/preconfigured duration. At the expiryof an extended scheduling period, the WTRU may stop monitoring for aWTRU specific identity (e.g., a C-RNTI and/or temporary C-RNTI and/orany other identity used for the purposes of data transmission). The WTRUmay continue and/or start monitoring using a P-RNTI (e.g., for pagingreception) while in an INACTIVE state.

The WTRU may be configured with one or more functions associated to theRRC CONNECTED state when in NR-INACTIVE state. The WTRU may beconfigured with dedicated resources for scheduling request (e.g., D-SRon PUCCH and/or equivalent). The WTRU may use such resource if the WTRUhas valid uplink timing alignment (e.g., instead of initiating thetransmission of a preamble). The WTRU may consider such configurationinvalid if it determines that it no longer has valid uplink timingalignment, and/or when the extended scheduling period has ended (e.g.,the timer Tschext has expired).

A WTRU may be configured to perform security handling regarding aspectsof a Light Connectivity/INACTIVE state. For example, an RRC message, RRCsignaling, RRC PDU, RRC SDU, control message, control signaling,control, may be used to generally refer to any control data (e.g.,including such that may be carried within a MAC CE, if applicable)and/or data associated with a signaling radio bearer (SRB). Methodsdescribed herein may be applicable to other arrangements. For example,data, data PDU and/or data SDU may generally refer to any user planedata (e.g., including MAC CE e.g., for BSR, PHR, etc.) and/or dataassociated with a DRB. Methods described herein may be applicableindependently of state. Methods described herein may be applicable toCONNECTED state, and/or a similar state.

A security level may be associated with UL data transmission. A WTRU mayautonomously determine and/or apply a security level associated with aUL data transmission in INACTIVE state based on preconfigured rules.

Security levels may be different. Different security levels may bedetermined by the extent and/or coverage of integrity protection.Different security levels may be determined by the extent and/orcoverage of confidentiality protection. The extent and/or coverage ofconfidentiality protection may be determined by a security key material(for example, the freshness of the security key material, etc.).

Preconfigured rules may be provided. Preconfigured rules may be afunction of WTRU location, type of data, WTRU configuration aspect (forexample, as received from the network), time aspect (for example,associated with the security context, data activity, INACTIVE state etc.

For example, the security level may be associated with the extent and/orcoverage of integrity protection. For example, a WTRU may be configuredto integrity protect a complete transport block associated with theinitial data transmission. A WTRU may be configured to integrity protect(e.g., only) a portion of the transport block, and/or provide differentlevels of integrity protection for different portions of a transportblock. A WTRU may be configured to integrity protect (e.g., only) thesignaling message (e.g., RRC and/or data associated with a SRB) portionand/or the part of transport block carrying control fields (e.g., WTRUidentity/WTRU context identity). A WTRU may be configured to transmit acode associated with integrity protection (e.g., MAC-I), wherein thelength of the code (e.g., zero, short, normal etc.) may be determined byone or more preconfigured rules. A WTRU may be configured to transmit aMAC-I calculated over the locally stored ASN.1 encoded fields which mayinclude WTRU identity, and/or identity of the source cell, etc.

For example, the security level may be associated with the extent and/orcoverage of integrity protection. For example, a WTRU may be configuredto integrity protect the complete transport block associated with theinitial data transmission. A WTRU may be configured to integrity protect(e.g., only) a portion of the transport block, and/or a different levelof integrity protection for different portions of a transport block. AWTRU may be configured to integrity protect (e.g., only) the signalingmessage (e.g., RRC and/or data associated with a SRB) portion and/or thepart of transport block carrying control fields (e.g., WTRUidentity/WTRU context identity). A WTRU may be configured to transmit acode associated with integrity protection (e.g., MAC-I), wherein thelength of the code (e.g., zero, short, normal etc.) may be determined byone or more preconfigured rules. A WTRU may be configured to transmit aMAC-I calculated over the locally stored ASN.1 encoded fields which mayinclude WTRU identity, identity of the source cell, etc.

For example, the security level may be associated with the extent and/orcoverage of confidentiality protection. For example, a WTRU may beconfigured to encrypt the complete transport block associated with theinitial data transmission. A WTRU may be configured to provide differentlevels of confidentially protection for different portions of transportblock. A WTRU may be configured not to encrypt the signaling message(e.g., RRC message and/or data associated with a SRB) and/or parts oftransport block carrying control fields (e.g., WTRU identity/WTRUcontext identity), but to encrypt the data portion of the transportblock.

For example, the security level may be associated with thecharacteristics of a security context and/or type of security key and/orsecurity algorithm.

For example, the security level may be associated with the freshness ofa security key material. For example, a WTRU may be configured to usethe same key and/or security context used in the source cell based on apreconfigured rule. When using the same key as source cell, the WTRU maybe configured store the PDCP COUNT value prior to entering INACTIVEstate and/or continue the PDCP sequence number for data transmissions inINACTIVE state. A WTRU may be configured to derive a new key wheninitial data transmission in triggered while in INACTIVE state, forexample, when the WTRU is not in an extended scheduling period and/orwhen a signaling procedure is not ongoing. The WTRU may derive a new keybased on stored security context and/or one or more additionalparameters, for example a NCC (Next Hop Chaining Count) parameterassociated with the cell in which data transmission is triggered (e.g.,EARFCN, PCI), identity associated with WTRU in INACTIVE state (WTRUcontext ID and/or resume ID etc.), identity associated with an area(e.g., RAN area ID). When deriving the new key, the WTRU may beconfigured to reset the PDCP COUNT to 0.

A security level may also be associated with the order in whichencryption and/or integrity protection is applied. For example, the WTRUmay apply ciphering (thus excluding e.g., A MAC-I field and/or settingthe corresponding bits to a specific value e.g., 0). A WTRU may applyintegrity protection for a first uplink transmission after keyderivation is performed. A WTRU may apply ciphering, for example, beforeintegrity protection, and/or conversely otherwise. For example, the WTRUmay perform integrity protection verification and/or may applydeciphering (thus excluding e.g., A MAC-I field and/or setting thecorresponding bits to a specific value e.g., 0) for a downlinktransmission after key derivation is performed.

For example, a WTRU may be configured with one or more or combination ofabove methods to realize a specific security level.

For example, the preconfigured rule may include an aspect associatedwith WTRU location. For example, WTRU may apply a security level for adata transmission in the same cell in which WTRU entered the INACTIVEstate. This may be different than a security level for data transmissionin any other cell. A WTRU may apply a security level for a datatransmission in the cells of a cell group in which the WTRU enteredINACTIVE state, different than the security level for data transmissionin any other cell group. For example, such cell group may aconfiguration aspect of the WTRU. Such cell group may e.g., correspondto cells of a same eNB, and/or correspond to cells with a common PDCPanchor. A WTRU may apply a security level for a data transmission in alogical area (e.g., RAN area) in which the WTRU entered INACTIVE state,different than the security level for data transmission in any otherlogical area (e.g., RAN area).

A WTRU may determine the applicable security level (and/or applicablesecurity parameters) as a function of whether the transmission is usingresources of a cell (and/or associated with a cell group) thatcorresponds to a cell (and/or a cell group) in which the WTRU lastsuccessfully performed a transmission with a given security level. AWTRU may determine that the same security level and/or the same securitycontext is applicable when such is the case, possibly if other criterion(e.g., security context validity, type of data, and/or required securitylevel equal or less than the last used security level, etc.) are alsomet. A comparison may be triggered upon arrival of control and/or userplane data at the WTRU for which security is applicable in the UL and/orDL direction.

For example, the preconfigured rule may include an aspect associatedwith prior WTRU activity in the cell and/or cell group. For example, aWTRU may apply a previous security level that is equal or higher thanthe one determined for the transmission, if that security level is stillvalid. For example, if the WTRU can determine it is performing atransmission in the same cell and/or cell associated to a cell group. AWTRU may apply the security level applied for a signaling procedure(e.g., an area update procedure) for the future data transmissionprocedure in the same cell.

For example, the preconfigured rule may include an aspect associatedwith a type of transmission in the cell. For example, a WTRU may apply asecurity level for data transmission for initial transmission in a celldifferent than the security level for subsequent/future datatransmission in the same cell and/or cell group, e.g., as a function ofthe received response and/or scheduling.

For example, the preconfigured rule may be a function of type of data totransmit. For example, a WTRU may apply a security level for controlplane signaling different than the user plane data. A WTRU may apply adifferent security level for different types of control signaling basedon message type (e.g., resume and/or re-establishment) and/or bearer onwhich the specific control message is transmitted, e.g., SRB0 and/orSRB1. A WTRU may apply a security level for a user plane datamultiplexed with control plane signaling different from user plane data(e.g., by itself).

For example, the preconfigured rule may be a function of freshnesscriteria. For example, a WTRU may determine to apply a specific securitylevel (e.g., derive a new security key) when a determined/preconfiguredtime elapses since the WTRU was in an INACTIVE state. A WTRU maydetermine to apply a specific security level when adetermined/preconfigured time elapses since the last key derivation. AWTRU may determine to apply a specific security level when a specificPDCP COUNT value has already been used for this specific key and/orradio bearer. A WTRU may determine to apply a specific security levelwhen a preconfigured time elapses since a last data transmission. A WTRUmay determine to apply a specific security level as a function ofanother freshness criteria, e.g., when the WTRU determines from suchcriteria that a specific security level may be applied and/or that theWTRU may derive a new set of key(s).

For example, a WTRU may receive control signaling that indicates thatthe WTRU may (e.g., should) transition to, or remain in, the INACTIVEstate. The control signaling may include a next hop chaining count,e.g., for new key derivation. The WTRU may determine that new securitykeys may (e.g., should) be generated when a transmission (e.g., DLand/or UL) is initiated following a determination that the WTRU may(e.g., should) re-establish the PDCP entity. The WTRU may determine thatnew security keys may (e.g., should) be generated when the WTRUdetermines that a specific PDCP COUNT value associated with atransmission has already been used for the current key for the concernedradio bearer. When the WTRU determines that a specific PDCP COUNT valueassociated with a transmission has already been used for the current keyfor the concerned radio bearer, among other scenarios, the WTRU mayinitiate a recovery procedure e.g., if key derivation might not beperformed. For example, the recovery procedure may be a connectionestablishment procedure and/or a re-establishment procedure. Forexample, the WTRU may activate of a new security context with thenetwork using a connection establishment procedure and/or may derive newsecurity keys using a re-establishment procedure.

A WTRU may assume the new key generated as a result of elapsed keyfreshness criteria as the key used for a most recent successfultransmission with security applied. A WTRU may trigger a UL signalingmessage when the freshness criteria associated with the stored securitycontext is elapsed. A WTRU may either receive a new key as a result ofsuch signaling procedure and/or assume that the autonomously derived keyis valid upon successful competition of such signaling procedure.

For example, the preconfigured rule may be explicitly configured. Forexample, a WTRU may receive a configuration. A WTRU may receive asecurity level configuration specific to DRBs. A WTRU might not transmitan RRC message if a DRB is configured to be of a lower security level. AWTRU may be configured not to perform integrity protection for UL datatransfers without a RRC message. A WTRU may determine to use the highestsecurity level for the transmission associated with data included in thetransmission, for example, when different security levels may beconfigured for different type of data.

A WTRU may be configured with one or more (and/or a combination of)methods described to determine a security level associated with datatransmission in an INACTIVE state.

A WTRU may be configured to determine a PDU structure for UL datatransmission in an INACTIVE state based on a security level associatedwith such transmission. A PDU structure may imply one or more of thefollowing: presence/absence of fields, values of fields (e.g.,indication of aspect related to security level), lengths of fields, etc.A WTRU may transmit an indication of security key material used forprotection (e.g., integrity and/or ciphering) for a data transmission inthe INACTIVE state using information. For example, a WTRU may indicatewhether integrity protection and/or ciphering is applied to the UL dataand/or parts thereof during data transmission in INACTIVE state. Suchindications may be transmitted in an element of RRC message and/or PDCPheader and/or MAC CE.

For example, a WTRU in an INACTIVE state upon arrival of UL data mayapply the same security algorithm that was used in the most recentsuccessful data transmission with security applied. A WTRU may performsuch determination, irrespective of whether the current serving cellsupports such security algorithm. A WTRU may perform such determinationirrespective of the security level associated with the data for thetransmission. A WTRU may perform such determination if such associatedsecurity level is equal or less than the security associated with suchmost recent successful data transmission with security applied.

For example, a WTRU in an INACTIVE state upon arrival of UL data, maydetermine a (e.g., useful) presence of an RRC message in one or more ofthe following, where a WTRU may transmit UL data: without an RRCmessage, perhaps for example if the current serving cell is the same asthe cell and/or cell group in which it last performed a successfultransmission with security applied; without an RRC message, perhaps forexample if no RRC message (e.g., area update) is pending fortransmission; in a DRB without an RRC message, perhaps for example ifindicated in an explicit configuration for such DRB; without an RRCmessage, perhaps for example if the size of UL resources (e.g.,preconfigured and/or received in a RAR and/or in any other schedulinggrant) cannot fit a RRC message. A WTRU may determine the length of aMAC-I to be included with the UL data as a function of the UL grant;without an RRC message, perhaps for example, if a freshness criteriaassociated with the security context is not elapsed; with an RRCmessage, perhaps for example if one or more of the aforementionedfactors are not satisfied; and/or with an RRC message, perhaps forexample upon a failure of a previous transmission without an RRCmessage.

For example, a WTRU in an INACTIVE state upon arrival of UL data, maydetermine to perform key derivation as a function of one or more of thefollowing. A WTRU may derive a new key, perhaps for example, if the ULdata is transmitted with the RRC message. A WTRU may derive a new key,perhaps for example, if the UL data is a signaling message. A WTRU mayuse a stored key, perhaps for example, if the current serving cell issame as the cell and/or cell group in which it last performed asuccessful transmission with security applied. A WTRU may derive a newkey otherwise. A WTRU may derive a new key, perhaps for example, if oneor more of a preconfigured freshness criteria/rules are elapsed. A WTRUmay derive a new key, perhaps for example, if it receives an explicitcommand, e.g., as a response to previous transmission with stored key. AWTRU may be configured to derive a new key by default for one or more,or all, UL transmissions in an INACTIVE state.

A WTRU in INACTIVE state derive a new key in one or more ways. The WTRUmay be configured with a NCC as a part of INACTIVE state context, and/orthe WTRU may compare the NCC value associated with INACTIVE state withthe NCC value associated with the most recent successful transmissionwith security applied. The NCC values may be equal, and/or the WTRU mayperform horizontal key derivation (e.g., using current K_(eNB) to derivethe K_(eNB*)). A WTRU may perform vertical key derivation (e.g., usingNH to derive the new K_(eNB*)). A WTRU may derive the integrity and/orciphering keys associated with the new key.

The WTRU might not be configured with NCC as a part of INACTIVE statecontext and/or one or more rules may require/use a new key, and/or theWTRU may perform horizontal key derivation (e.g., using current K_(eNB)to derive the K_(eNB*)). A WTRU may derive the integrity and/orciphering keys associated with the new key.

A WTRU in an INACTIVE state upon arrival of UL data may reset the PDCPCOUNT value if a new key is generated. The WTRU may continue the PDCPCOUNT value if an old/stored key is used.

A WTRU in an INACTIVE state upon arrival of UL data may attach a WTRUidentity with the UL data transmission in one or more of the followingways. UL data may be multiplexed with a RRC message, and/or the WTRU mayinclude the WTRU identity associated with INACTIVE state in the RRCmessage. The RRC message, and/or the part with the WTRU identity, mightnot be ciphered. UL data might not be multiplexed with a RRC message.The WTRU may include the WTRU identity associated with an INACTIVE statein a PDCP header. The part of the PDCP PDU with the WTRU identity mightnot be ciphered. UL data might not be multiplexed with a RRC message,and/or the WTRU may include the WTRU identity associated with INACTIVEstate in a MAC CE and/or add a MAC sub-header with a LCID indicating thetype of MAC CE carrying WTRU ID. The MAC CE and/or MAC sub-header mightnot be ciphered.

A WTRU may be configured to provide confidentiality and/or integrityprotection for the UL data transmission in one or more of the followingways.

UL data may be multiplexed with a RRC message. A WTRU may calculate theMAC-I over the ASN.1 encoded portion of a local variable that mayinclude a WTRU Identity associated with the INACTIVE state and/or PCI,Cell ID and/or cell group identity associated with the cell where theWTRU last performed a successful data transmission with security appliedand/or any other identity known at the WTRU and/or the network. Forcalculating MAC-I, the WTRU may assume that COUNT, BEARER, and/orDIRECTION are set to binary ones and/or value associated with currenttransmission and/or any other predefined value. The WTRU may include thecalculated MAC-I in the RRC message. The WTRU may determine the lengthof MAC-I based on the security level associated with the datatransmission.

UL data may be multiplexed with a RRC message. A WTRU may cipher thedata as part of the PDCP PDU associated with the DRB. A WTRU may deliverthe RRC message over SRB0.

UL data might not be multiplexed with a RRC message. A WTRU maycalculate a MAC-I over the PDCP header including the WTRU identityand/or the data part of the PDCP PDU, perhaps for example beforeencryption. The WTRU may append such a MAC-I, and/or others, to the endof the data part of PDCP PDU.

A WTRU may calculate the MAC-I over the ASN.1 encoded portion of a localvariable that may include a WTRU Identity associated with INACTIVE stateand/or PCI, Cell ID and/or cell group identity associated with the cellwhere the WTRU last performed a successful data transmission withsecurity applied with COUNT, BEARER, and/or DIRECTION set to binary onesand/or value(s) associated with current transmission and/or any otherpredefined value. The WTRU may append such a MAC-I, and/or others, tothe end of the data part of PDCP PDU.

A WTRU may transmit MAC-I in a MAC CE and/or indicate the type of MAC CEcarrying MAC-I, perhaps for example using a reserved LCID in the MACsub-header.

A length of a MAC-I may be zero or substantially zero. For example, thelength of the MAC-I may be zero, short, or normal based on the securitylevel associated with the data transmission. A WTRU might not applyintegrity protection to the UL data transmission.

A WTRU may cipher the data part of the PDCP PDU associated with the ULdata and/or the MAC-I if included.

Similar methods may be applied for reception of downlink data whenapplying security-related processing (e.g., deciphering, and/orintegrity protection verification, etc.).

One or more methods for handling response to UL data transmission may beprovided. A WTRU might not receive a response to an initial UL datatransmission. The WTRU may retry the UL data transmission for apredefined number of times, perhaps using same security context (e.g.,keys, and/or COUNT value, etc.) used for the initial transmission.

A WTRU may be configured to verify the authenticity of the response tothe UL data transmission in an INACTIVE state. The WTRU may perform anintegrity check on the received response using one or more of thefollowing methods, the WTRU may receive a response PDU with a MAC-Iattached in a MAC CE and/or PDCP PDU and/or in a RRC message. The WTRUmay calculate MAC-I using the same security context as UL, over theASN.1 encoded portion of a local variable and/or over the parts ofreceived DL PDU that includes WTRU Identity associated with INACTIVEstate and/or PCI, Cell ID and/or cell group identity associated with thecell where the WTRU last performed a successful data transmission withsecurity applied and/or PCI, Cell ID and/or cell group associated withthe current serving cell and/or any other identity known at the WTRUand/or the network with COUNT, BEARER and/or DIRECTION set to binaryones and/or a value associated with a current transmission and/or anyother predefined value.

The WTRU may consider the received response to be authentic, perhaps forexample, if the calculated MAC-I matches with the received MAC-I. TheWTRU may identity ciphered elements using the same security context asin the UL. The WTRU may consider the received response to be authentic,perhaps for example if the decrypted WTRU Identity matches with the WTRUidentity transmitted with the UL data.

A WTRU may receive a response indicating a security failure and/or ifthe WTRU might not verify the authenticity of the received response, theWTRU may do one or more of the following. The WTRU may delete the newkey (e.g., if derived) and/or fall back to the old key and/or securitycontext. The WTRU may consider the current cell as barred, performautonomous mobility to a different cell, and/or retry the UL datatransmission while in the INACTIVE state. The WTRU may be configured toreport such failures in a UL signaling message; exit the INACTIVE state;delete the WTRU context associated with an INACTIVE state (e.g.,including new and/or old keys); and/or perform a connectionestablishment. The WTRU may provide a reason for connectionestablishment (e.g., security failure in an INACTIVE state). The WTRUmay indicate the WTRU identity associated with the INACTIVE state in theconnection establishment.

A new key derivation may be performed during UL data transmission. AWTRU may consider the key derivation to be successful, perhaps forexample upon verifying the authenticity of the response to such ULtransmission. A WTRU may consider the UL data transfer to be successful,perhaps for example upon verifying the authenticity of the response tosuch UL transmission. The WTRU may use the verified security context forfurther key derivation and/or data transmission in the INACTIVE and/orCONNECTED state.

Methods for determining a security level associated with DL datatransmission may be provided. A WTRU may be configured to receive and/orprocess encrypted and/or integrity protected DL data while staying inINACTIVE state. A WTRU may determine a security level associated withthe DL data transmission to decrypt and/or verify the authenticity ofreceived DL data transmission in an INACTIVE state based on one or morepreconfigured rules.

A WTRU may receive DL paging with DL data and/or may send a responseindicating successful reception of paging message and/or successfulreception of DL data and/or successful security processing of DL data inone or more UL response message. A WTRU may be configured with apredefined time/frequency relation between DL paging and DL data.

A WTRU may receive DL paging and/or may transmit a UL response beforereceiving DL data. A WTRU may perform security processing for the ULresponse. For example, a WTRU may integrity protect and/or cipher partsand/or whole paging response message with old and/or new keys.

For example, a WTRU may employ one or more methods where DL data may beconsidered as a DL paging message and/or a UL response may be construedas a UL paging response.

In order to process DL data, a WTRU may apply the same securityalgorithm that was used in the most recent successful data transmissionwith security applied. A WTRU may perform such determinationirrespective of whether the current serving cell supports such securityalgorithm. A WTRU may perform such determination irrespective of thesecurity level associated with the data for the transmission. A WTRU mayperform such determination if such associated security level is equal orless than the security associated with such most recent successful datatransmission with security applied.

For example, a WTRU in an INACTIVE state upon arrival of DL data and/orDL paging addressed for the WTRU may determine to derive a (e.g., newand/or previously unused) key under one or more circumstances, such asone or more of the following. The WTRU may use a stored key, perhaps forexample if the current serving cell is same as the cell and/or cellgroup in which it last performed a successful transmission with securityapplied. WTRU may derive a new key, perhaps for example if the DL dataand/or DL paging message includes a NCC. The WTRU may derive a new key,perhaps for example if the DL data is transmitted with a RRC message.The WTRU may derive a new key, perhaps for example if (e.g., explicitly)indicated in the DL data PDU (e.g., in a PDCP header and/or MAC CE/header). The WTRU may derive a new key, perhaps for example if the DLpaging associated with the DL data transmission indicates that the DLdata PDU is encrypted. The WTRU may derive a new key, perhaps forexample if one or more of preconfigured freshness criterion/ruleselapsed before the DL data transmission. The WTRU may be configured toderive a new key, perhaps for example by default for one or more, orall, DL transmissions in INACTIVE state.

For example, a WTRU in an INACTIVE state may derive a new key in one ormore of the following ways, for example if the WTRU determines new keymay be useful.

The WTRU may be configured with a NCC as a part of INACTIVE statecontext and/or the DL transmission might not include a NCC value. TheWTRU may compare the NCC value associated with the INACTIVE state withthe NCC value associated with the most recent successful transmissionwith security applied.

The WTRU may compare the NCC value associated with the INACTIVE statewith the NCC value associated with DL data transmission.

The WTRU may compare the NCC value received in the DL transmission withthe NCC value associated with the most recent successful transmissionwith security applied.

One or more rules may use a new key. The NCC values may be equal and/ormay be considered to be equal. The NCC values may be equal. The WTRU mayperform horizontal key derivation. (e.g., using current K_(eNB) toderive the K_(eNB*)). The NCC values might not be equal. The WTRU mayperform vertical key derivation (e.g., using NH to derive the newK_(eNB*)). The WTRU may derive the integrity and/or ciphering keysassociated with the new key. The WTRU may use the stored key and/or theassociated integrity and/or ciphering key.

For example, a WTRU in an INACTIVE state upon arrival of DL data mayreset the PDCP COUNT value if a new key is generated. The WTRU maycontinue the PDCP COUNT value if an old/stored key is used.

For example, a WTRU may be configured to perform an integrity check onthe received DL PDU using one or more of the following methods.

A WTRU may receive a DL PDU with MAC-I attached in a MAC CE and/or PDCPPDU and/or in a RRC message. The WTRU may calculate MAC-I using the samesecurity context as UL, over the ASN.1 encoded portion of a localvariable, and/or over the parts of received DL PDU that may include anWTRU Identity associated with an INACTIVE state and/or PCI, Cell ID,and/or cell group identity associated with the cell where the WTRU lastperformed a successful data transmission with security applied and/orPCI, Cell ID and/or cell group associated with the current serving celland/or any other identity known at the WTRU and/or the network withCOUNT, BEARER and/or DIRECTION set to binary ones and/or a valueassociated with current transmission and/or any other predefined value.The WTRU may consider the received response to be authentic, perhaps forexample if the calculated MAC-I matches with the received MAC-I.

A WTRU may receive a DL PDU with the WTRU identity ciphered using thesame security context as in the UL. The WTRU may consider the receivedDL PDU to be authentic if the decrypted WTRU Identity matches with theWTRU identity associated with INACTIVE state.

For example, the WTRU may be configured to decipher the data part of thePDCP PDU associated with the DL data, and/or the MAC-I if included.

A WTRU may employ a transmission of a response to a DL transmission. Forexample, perhaps upon receiving a DL PDU, a WTRU may be configured toindicate one or more of the following in the UL response: anacknowledgement indicating successful reception of DL paging message(e.g., if present/applicable); an acknowledgement indicating asuccessful reception of the DL data PDU; may (e.g., implicitly) indicatethe reception of a paging message, perhaps for example, if anacknowledgement of DL data PDU is included in the UL response; a successand/or failure associated with the outcome of security processing of thereceived DL data; and/or a parameter/code (e.g., MAC-I) to prove theauthenticity of the WTRU. A WTRU may (e.g., implicitly) indicate thesuccess of security processing by inclusion of the MAC-I in the ULresponse message.

Upon verifying the integrity of the DL data, a WTRU may transmit aresponse on the UL including a MAC-I determined using methods describedherein. A WTRU may derive a new key based on parameters received in theDL data, perhaps to determine the MAC-I included in the UL responsemessage.

For example, the WTRU may transmit a UL response in a RRC message if DLdata was multiplexed with a RRC message. For example, the WTRU maytransmit a UL response in a MAC CE if DL data was not multiplexed withRRC message. For example, the WTRU may transmit a UL response in a RRCmessage if a new security key was derived for processing DL data.

Perhaps for example upon a security failure (e.g., an integrity checkfail) associated with the DL data reception, a WTRU may perform one ormore of the following, the WTRU may: delete the new key (perhaps forexample, if derived) and/or fall back to the old key and/or securitycontext. The WTRU may consider the current cell as barred and/or performautonomous mobility to a different cell. The WTRU may be configured toreport such failures in a UL signaling message; and/or exit the INACTIVEstate, delete the WTRU context associated with INACTIVE state (e.g.,including new and/or old keys) and/or perform a connectionestablishment. The WTRU may provide a reason for connectionestablishment (e.g., security failure in INACTIVE state). The WTRU mayindicate the WTRU identity associated with the INACTIVE state in theconnection establishment.

A WTRU may be configured to handle and/or recover from one or moreunexpected security-related events. A WTRU may determine that a specificsecurity level may (e.g., should) be applied. When the WTRU does notperform and/or complete one or more steps to enable the specificsecurity level, the WTRU may initiate a recovery procedure.

For example, a WTRU might not have sufficient, valid, and/or up-to-datesecurity parameters for performing a proper key derivation. For example,the WTRU may determine that one or more security parameters areinsufficient, invalid, and/or outdated. The one or more securityparameters may be associated with a key derivation. The WTRU mayinitiate a recovery procedure based on the determination that one ormore security parameters are invalid, insufficient, and/or outdated. TheWTRU may determine that data is being retransmitted using a differentkey but with the same count value (e.g., different keys may be usedwithout re-initialing a COUNT value). The WTRU may determine that datais being retransmitted using a same key but with a different countvalue. The WTRU may determine that a count value has already been usedfor a bearer (e.g., a concerned bearer) since the last time the WTRU hasperformed a key update. The WTRU may determine that a count value hasalready been used for a bearer (e.g., a concerned bearer) since the lasttime the WTRU has performed a key derivation. The count value may beapplicable to a transmission. The WTRU may determine that the countvalue has wrapped around the bearer since the last time the WTRU hasperformed a key update.

The WTRU may determine that the count value has wrapped around thebearer since the last time the WTRU has performed a key derivation. TheWTRU may determine that one or more security parameters for a securitylevel (e.g., a concerned security level) are no longer valid and/orup-to-date based on the reception of a system signature. The WTRU maydetermine that one or more security parameters for a security level(e.g., a concerned security level) are no longer valid and/or up-to-datebased on a change in the applicable system signature. The WTRU maydetermine that one or more security parameters for a security level(e.g., a concerned security level) are no longer valid and/or up-to-datebased on a change in the applicable area (e.g., tracking area and/or thelikes). The WTRU may determine that one or more security parameters fora security level (e.g., a concerned security level) are no longer validand/or up-to-date based on an indication in the System Information.

The WTRU may determine that one or more security parameters for asecurity level are no longer valid and/or up-to-date after (e.g., upon)expiration of a validity period. The WTRU may determine that one or moresecurity parameters for a security level are no longer valid and/orup-to-date based on an indication (e.g., in a response) from thenetwork. For example, the WTRU may determine that one or more securityparameters for a security level are no longer valid and/or up-to-datebased on reception of a random access response. For example, the WTRUmay determine that one or more security parameters for a security levelare no longer valid and/or up-to-date based on a reception of a responseduring the area update procedure.

For example, a recovery procedure may be a connection establishmentprocedure (e.g., that may use the activation of a new security contextwith the network) and/or a re-establishment procedure (e.g., that mayenable the derivation of one or more new security keys).

The processes described above may be implemented in a computer program,software, and/or firmware incorporated in a computer-readable medium forexecution by a computer and/or processor. Examples of computer-readablemedia include, but are not limited to, electronic signals (transmittedover wired and/or wireless connections) and/or computer-readable storagemedia. Examples of computer-readable storage media include, but are notlimited to, a read only memory (ROM), a random access memory (RAM), aregister, cache memory, semiconductor memory devices, magnetic mediasuch as, but not limited to, internal hard disks and removable disks,magneto-optical media, and/or optical media such as CD-ROM disks, and/ordigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, terminal, base station, RNC, and/or any host computer.

What is claimed is: 1-53. (canceled)
 54. A wireless transmit/receiveunit (WTRU) comprising a receiver, a transmitter, and a processor,wherein: the receiver is configured while in a radio resource control(RRC) Connected state to: receive, from a network entity, (i) anindication to the WTRU to transition to a RRC Inactive state and (ii)any one or more of an indication of (a) one or more logical channels(LCHs) or (b) one or more radio bearers that are configured for uplink(UL) transmission while the WTRU is in the RRC Inactive state; theprocessor is configured to: transition the WTRU from the RRC Connectedstate to the RRC Inactive state; and the transmitter is configured to:in accordance with (1) the WTRU being in the RRC Inactive state, (2) ULdata associated with the indicated one or more LCHs or radio bearersbecoming available for transmission, and (3) the UL data satisfying acriterion that a total amount of the UL data is less than a threshold,transmit the UL data, while remaining in the RRC Inactive state.
 55. TheWTRU of claim 54, wherein the transmitter is further configured to:transmit an identity of the WTRU while in the RRC Inactive state. 56.The WTRU of claim 54, wherein the transmitter is further configured to:on condition that the WTRU is in the RRC Inactive state, and UL dataassociated with a LCH not among the indicated one or more LCHs becomesavailable for transmission, transmit an identity of the WTRU and an RRCmessage to request the WTRU to transition back to the RRC Connectedstate.
 57. The WTRU of claim 54, wherein the transmitter is furtherconfigured to: on condition that the WTRU is in the RRC Inactive state,and UL data associated with a radio bearer not among the indicated oneor more radio bearers becomes available for transmission, transmit anidentity of the WTRU and an RRC message to request the WTRU totransition back to the RRC Connected state.
 58. The WTRU of claim 54,wherein the transmitter is configured to: on condition that the WTRU isin the RRC Inactive state, and UL data associated with any one or moreof 1) the indicated one or more LCHs or 2) the indicated one or moreradio bearers becomes available for transmission, and the UL data isgreater than the threshold, transmit a RRC message to request the WTRUto transition back to the RRC Connected state.
 59. The WTRU of claim 58,wherein the transmitter is further configured to: transmit an identityof the WTRU while in the RRC Inactive state.
 60. The WTRU of claim 54,wherein the UL data is in a buffer of the WTRU when becoming availablefor transmission.
 61. The WTRU of claim 54, wherein the UL data furthersatisfies a criterion that a size of an available UL grant canaccommodate the total amount of the UL data.
 62. The WTRU of claim 54,wherein the processor is further configured to monitor a control channelfor a time duration after the UL data is transmitted in the RRC Inactivestate.
 63. A method used by a wireless transmit/receive unit (WTRU) forwireless communications, the method comprising: receiving, from anetwork entity, while in a radio resource control (RRC) Connected state,(i) an indication to the WTRU to transition to a RRC Inactive state and(ii) any one or more of an indication (a) of one or more logicalchannels (LCHs) or (b) one or more radio bearers that are configured foruplink (UL) transmission while the WTRU is in the RRC Inactive state;transitioning the WTRU from the RRC Connected state to the RRC Inactivestate; and in accordance with (1) the WTRU being in the RRC Inactivestate, (2) UL data associated with the indicated one or more LCHs orradio bearers becoming available for transmission, and (3) the UL datasatisfying a criterion that a total amount of the UL data is less than athreshold, transmitting the UL data while remaining in the RRC Inactivestate.
 64. The method of claim 63, further comprising: transmitting anidentity of the WTRU while in the RRC Inactive state.
 65. The method ofclaim 63, further comprising: on condition that the WTRU is in the RRCInactive state, and UL data associated with a LCH not among theindicated one or more LCHs becomes available for transmission,transmitting an identity of the WTRU and an RRC message to request theWTRU to transition back to the RRC Connected state.
 66. The method ofclaim 63, further comprising: on condition that the WTRU is in the RRCInactive state, and UL data associated with a radio bearer not among theindicated one or more radio bearers becomes available for transmission,transmitting an identity of the WTRU and an RRC message to request theWTRU to transition back to the RRC Connected state.
 67. The method ofclaim 63, further comprising: on condition that the UL data associatedwith any one or more of 1) the indicated one or more LCHs or 2) theindicated one or more radio bearers becomes available for transmission,and the UL data is greater than the threshold, transmitting a RRCmessage to request the WTRU to transition back to the RRC Connectedstate.
 68. The method of claim 67, further comprising: transmitting anidentity of the WTRU while in the RRC Inactive state.
 69. The method ofclaim 63, wherein the UL data is in a buffer of the WTRU when becomingavailable for transmission.
 70. The method of claim 63, wherein the ULdata further satisfies a criterion that a size of an available UL grantcan accommodate the total amount of the UL data.
 71. The method of claim63, further comprising: monitoring of a control channel for a timeduration after the UL data is transmitted in the RRC Inactive state.